JPH06165220A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To satisfactorily compensate the time base error of a reproduction video signal in a VTR using a rotary head. CONSTITUTION:A pilot signal having a frequency which is the integer multiple of a horizontal synchronizing frequency is frequency-multiplexed and recorded in a band between a luminance signal whose frequency is modulated and a low pass conversion chrominance signal, in the VTR of a color under system. At the time of reproduction, the reproduction pilot signal is separated by a BPF 43, a writing clock phase-following the reproduction pilot signal is generated by a PLL circuit 46, and the time base correction of the reproduction video signal is operated based on the writing clock.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus such as a VTR (Video Tape Recorder) having means for correcting a time base fluctuation of a reproduced video signal.

[0002]

2. Description of the Related Art A video signal recorded / reproduced by a VTR using a rotary head contains time-axis fluctuation so-called jitter due to rotation unevenness of the rotary head or running unevenness or vibration of a magnetic tape. If there is jitter in the reproduced color signal, it is not possible to follow such jitter due to the narrow pull-in range of the APC (auto phase compensate) circuit of the television. Recording and reproduction are performed as shown.

The video signal is first separated into a luminance signal and a chrominance signal, the luminance signal is frequency-modulated, the carrier color signal is converted to a low frequency, and then mixed with the luminance signal and recorded on a magnetic tape. During reproduction, the frequency-modulated luminance signal is frequency-demodulated to obtain a reproduced luminance signal. The reproduced low-frequency conversion carrier color signal is converted to the original color subcarrier frequency by frequency conversion.At this time, a signal containing jitter is generated by the horizontal sync signal separated from the reproduced luminance signal, and this signal is pulled in. The phase of the carrier color signal is stabilized by the heterodyne principle by using the APC circuit having a wide range.
Such a recording / reproducing system is called a color under system.

In such a color-under type VTR, the reproduced luminance signal still contains the jitter, and the reproduced carrier color signal has the jitter corrected only with respect to the color subcarrier. However, there is a jitter related to the baseband signal of the color signal.
For this reason, VTRs with large screens and high image quality of televisions
With the spread of the above, it is desired to correct these jitters, and the time axis correction device shown in FIG. 10 has been conventionally used.

In FIG. 10, a reproduction luminance signal from a magnetic recording / reproducing device or a reproducing device (not shown) is input to a terminal 120, and a reproduction carrier color signal is also input to a terminal 121. Each of these signals contains jitter. Sync separation circuit 70, phase comparator 71, frequency divider 7
2, LPF 73 and VCO (voltage controlled oscillator) 122
The jitter of the reproduced video signal is obtained by using the horizontal synchronizing signal of the reproduced luminance signal, and the write clock synchronized with the jitter is generated. With this write clock, the reproduced luminance signal is quantized by the ADC (A / D converter) 35, and the carrier color signal is demodulated by the color decoder 39. RY and B-
The two color difference signals of Y are quantized by the ADC 40 and the ADC 41, respectively, and written in the memory 42. The reproduced video signal, that is, the reproduced luminance signal and the two color difference signals are written in the memory 42 as digital data whose jitter is corrected at this point. These data are used as the reference signal generator 5
Read with the reference clock generated in step 8, DAC (D / A
By performing D / A conversion in the converter) 52, the DAC 53, and the DAC 54, the reproduced luminance signal, the R-Y signal, and the B-Y signal whose jitter has been corrected can be obtained. DAC52
The reproduced luminance signal from the
The −Y signal and the BY signal from the DAC 54 are modulated by the color encoder 55 to be a carrier color signal and output to the terminal 57. The memory control circuit 51 receives the write clock and the reference clock and writes / writes the memory 42.
Read (W / R) control and address control are performed.

The write clock synchronized with the jitter of the reproduced video signal has a center frequency of 4 with the color subcarrier frequency fsc.
Double frequency VCO 122. VC
The output of O122 is frequency-divided by the frequency divider 72 by 910, and this frequency-divided output is supplied to the phase comparator 71. The phase comparator 71 outputs a phase error between the horizontal sync signal from the sync separation circuit 70 and the output of the frequency divider 72, and this phase error is LP.
It is fed back to the VCO 122 via F73. As a result, the frequency of the write clock, which is the output of the VCO 122, follows the jitter of the video signal.

[0007]

In the above conventional time axis correction apparatus, since the jitter is detected based on the horizontal synchronizing signal of the reproduced video signal, the upper limit of the frequency of the detectable jitter is the horizontal synchronizing frequency. Where fh is a frequency up to fh / 2, a write clock that follows jitter in a higher frequency band cannot be generated any more, and therefore, there is a problem that a jitter correction effect cannot be sufficiently obtained. there were. Also, since the jitter is detected based on the horizontal sync signal, the jitter is relatively corrected on the left side of the screen, which is the portion near the horizontal sync signal of the video signal. However, there is a problem in that the image becomes larger and the image shake becomes larger.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and in recording, a frequency-modulated luminance signal obtained by frequency-modulating a carrier wave with a luminance signal of a video signal and a video signal of the video signal. A recording signal obtained by frequency-multiplexing a low-pass conversion color signal obtained by converting a color signal into a lower frequency band of the frequency-modulated luminance signal is recorded on a recording medium by a rotary head, and at the time of reproduction, from the recording medium. From the reproduced signal, the reproduced frequency-modulated luminance signal is demodulated to obtain a reproduced luminance signal, and the reproduced low frequency conversion color signal frequency-separated from the reproduced signal is converted to the original frequency to obtain a reproduced color signal. In this way, in the magnetic recording / reproducing apparatus having a time axis correcting means for obtaining the reproduced video signal and correcting the time axis fluctuation of the reproduced video signal, Generating means for generating a recording pilot signal having a frequency between the frequency-modulated luminance signal and the low-frequency conversion color signal; and the recording pilot signal, the frequency-modulated luminance signal and the low-frequency conversion color signal. Means for frequency-multiplexing the VCO, a separating means for separating the reproduced pilot signal from the reproduced signal, a VCO and the VCO
A first frequency divider for frequency-dividing the output signal of the VCO, and controlling the oscillation frequency of the VCO by a first phase error signal between the reproduction pilot signal and the output signal of the first frequency divider. A magnetic recording / reproducing apparatus comprising: a write clock generating unit that generates a write clock of the time axis correcting unit;

At the time of recording, a frequency-modulated luminance signal obtained by frequency-modulating a carrier wave with a luminance signal of a video signal and a low-pass conversion color obtained by converting a color signal of the video signal into a lower frequency band of the frequency-modulated luminance signal. A recording signal obtained by frequency-multiplexing a signal and a signal is recorded on a recording medium by a rotary head, and at the time of reproduction, a reproduced frequency-modulated luminance signal frequency-separated from the reproduced signal from the recording medium is demodulated to obtain a reproduced luminance signal. A time axis for obtaining a reproduced video signal by converting the reproduced low-frequency converted color signal frequency-separated from the reproduced signal into the original frequency to obtain a reproduced color signal, and correcting a time-axis fluctuation of the reproduced video signal. In a magnetic recording / reproducing apparatus provided with a correction means, a frequency that is an integer multiple of a horizontal synchronizing frequency of the video signal and that is between the frequency-modulated luminance signal and the low-frequency conversion color signal is set. Generating means for generating a recording pilot signal, a multiplexing means for frequency-multiplexing the recording pilot signal with the frequency-modulated luminance signal and the low frequency conversion color signal, and a separating means for separating the reproducing pilot signal from the reproducing signal. , VCO and a first frequency divider for dividing the output signal of the VCO, and the oscillation of the VCO by a first phase error signal between the reproduction pilot signal and the output signal of the first frequency divider. A write clock generating means for controlling a frequency to generate a write clock for the time axis correcting means, a signal obtained by dividing the output signal of the VCO by a second divider, and a horizontal synchronizing signal separated from the reproduced video signal. And a second phase error signal equal to or greater than the first predetermined value and equal to or less than the second predetermined value, the addition means adds the second phase error signal to the first phase error signal. Magnetic recording and reproducing apparatus, characterized in that the,

Further, the generating means generates the recording pilot signal so that the adjacent tracks of the tracks to be formed by the scanning of the rotary head have different frequencies, and the write clock generating means changes the frequency of the reproduction pilot signal. An object of the present invention is to provide a magnetic recording / reproducing device configured to switch the frequency division ratio in accordance with the above.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the magnetic recording / reproducing apparatus of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a recording system, FIG. 2 is a diagram showing a frequency spectrum of a recording signal, and FIG. 3 is a block diagram showing a reproducing system. In FIG.
The luminance signal and the carrier color signal of the video signal to be recorded are input to the terminals 1 and 7. The luminance signal recording processing circuit including the LPF 2, the pre-emphasis 3, the FM modulator 4 and the HPF 5 frequency-modulates the luminance signal and supplies it to the adder 6 as a frequency-modulated luminance signal. Also, BP
The color signal recording processing circuit including the F8, the frequency converter 9 and the LPF 10 frequency-converts the carrier color signal into a lower band of the frequency-modulated luminance signal, and adds the carrier color signal as a low-frequency converted carrier color signal by the adder 6 to Frequency-multiplexed with frequency-modulated luminance signal. The above configuration is the same as the configuration of the recording system in the conventional magnetic recording / reproducing apparatus.

On the other hand, the luminance signal input to the terminal 1 is also supplied to the sync separation circuit 13, and the sync separation circuit 13 separates the horizontal synchronization signal from the brightness signal, and the phase comparator 15
Supply to. Phase comparator 15, LPF 16, VCO 17
The frequency divider 18 and the frequency divider 18 constitute the PLL circuit 14, and generate a pilot signal having a frequency m times (where m is an integer) the horizontal synchronizing signal frequency fh. The sync separation circuit 13 and the PLL 14 are the generation means in the present invention. The center frequency of the VCO 17 is set to, for example, 91 × fh, and the frequency division ratio of the frequency divider 18 is set to 1 / m, for example, 1/91, so that a pilot signal having a frequency of about 1.4 MHz is generated. Occur. VPF at BPF19
The pilot signal from 17 is supplied to the adder 6 as a sine wave, and the adder 6 frequency-multiplexes the frequency-modulated luminance signal and the low-frequency conversion carrier color signal to record the recording signal with the video head 11 and the video head 12. Supply to. As a result, the recording signal is recorded on the magnetic tape (not shown). The video head 11 and the video head 12 are rotary heads attached to a rotary drum (not shown) so as to face each other by 180 degrees, and the magnetic tape is wound around the rotary drum at a wrap angle of 180 degrees or more. Then, one track is formed obliquely with respect to the magnetic tape per field of the video signal.

FIG. 2 shows the frequency spectrum of this recording signal. In FIG. 2, reference numeral 20 denotes a low-frequency conversion carrier color signal, which has a bandwidth of about 1 MHz centered at about 629 KHz, for example. Reference numeral 21 denotes a frequency-modulated luminance signal, which is, for example, 5.4 MHz to 7M.
Has a frequency shift width of Hz and the lower sideband is about 1.6 MHz
Has been extended to. Therefore, the pilot signal 22 of about 1.4 MHz has a frequency between the low frequency conversion carrier color signal 20 and the frequency-modulated luminance signal 21. When a plurality of signals are multiplexed and recorded, cross-modulation distortion occurs, and if a part thereof is within the band of the low-frequency conversion carrier color signal or the frequency-modulated luminance signal, the image quality deteriorates. Therefore, the recording level of the pilot signal 22 is set lower than the recording level of the low-frequency conversion carrier color signal so that the generated intermodulation distortion signal does not affect the reproduced image quality.

Further, the frequency division ratio of the frequency divider 18 is, for example, 1 /
70, the center frequency of the VCO 17 may be 70 × fh, and the frequency of the pilot signal 22 may be about 1.1 MHz. This frequency corresponds to the low-frequency conversion carrier color signal 2
The frequency almost coincides with the upper limit frequency of 0. But,
Since the energy of the low-frequency-converted carrier color signal 20 is concentrated near 629 KHz, the energy of the low-frequency-converted carrier color signal 20 near 1.1 MHZ is low, and there is almost no effect of frequency-multiplexing and recording the pilot signal 22. Therefore, it can be said that the 1.1 MHz pilot signal 22 is also recorded in the band between the low-frequency conversion carrier color signal 20 and the frequency-modulated luminance signal 21.

Next, the structure and operation of the reproducing system will be described with reference to FIG. The video head 11 and the video head 12 are magnetic heads for reproducing a recorded magnetic tape, and may be the same as the magnetic heads used in the recording system or may be magnetic heads for reproduction only.
The signals reproduced by the video head 11 and the video head 12 are alternately selected by the switch 30 to become continuous reproduction signals. The switch 30 is controlled by a switching signal described later.

The HPF 31, the FM modulator 32, the de-emphasis 33 and the LPF 34 frequency-demodulate the reproduced luminance signal from the switch 30 into the original luminance signal and output the original luminance signal. Further, the LPF 36, the frequency converter 37, and the BPF 38 frequency-convert the low-frequency conversion carrier color signal from the reproduced signal into a carrier color signal having the original frequency, and output the carrier color signal. Further, the color decoder 39 performs color demodulation of the carrier color signal from the BPF 38 and RY
And BY are demodulated into two color difference signals.

The reproduced luminance signal and the two color difference signals obtained as described above are set to A by a write clock described later.
The data is quantized by the DC 35, the ADC 40, and the ADC 41, and written in the memory 42. The reproduced video signal, that is, the reproduced luminance signal and the two color difference signals are written in the memory 42 as digital data whose jitter is corrected at this point. These data are read by the reference clock generated by the reference signal generator 58 and D / A converted by the DAC 52, the DAC 53, and the DAC 54, so that the reproduction luminance signal, the R-Y signal, and the B-Y corrected on the time axis, respectively. The signal is obtained. The reproduced luminance signal from the DAC 52 is the terminal 56.
To RY signal from DAC 53 and B from DAC 54
The -Y signal is modulated by the color encoder 55 to be a carrier color signal and output to the terminal 57. Memory control circuit 51
Is input with the clock and the reference clock, and the memory 42
Write / read control and address control are performed.

Writing to the memory 42 and ADCs 35 and 4
The write clock for sampling 0, 41 is generated as shown below. First, the BPF 43 separates the pilot signal from the reproduced signal, and the AGC 44 and the limiter 45 make the amplitude constant. Then, the pilot signal whose amplitude is made constant is supplied to the phase comparator 47,
PLL consisting of LPF 48, VCO 49 and frequency divider 50
Supply to the circuit 46. Here, the frequency division ratio of the frequency divider 50 is 1
/ N (for example, 1/10), and the center frequency of the VCO 49 is m × n × fh (for example, 910 × fh).
Then, the phase comparator 47 outputs the reproduction pilot signal and the VCO.
The phase error with the signal obtained by dividing the output signal of 49 by 1 / n is
Feedback to the VCO 49 through the LPF 48.
Therefore, the frequency of the reproduced pilot signal (m × fh)
The write clock having a frequency obtained by multiplying by n is output from the VCO 49. Since the reproduced pilot signal has the same jitter as the reproduced video signal, the frequency of the write clock output from the VCO 49 follows the jitter. Based on this write clock, the jitter of the video signal is corrected in the same manner as described in the conventional example.
As described above, since the write clock is an integral multiple of the horizontal synchronizing signal frequency, the frequency of the pilot signal for generating the write clock is also an integral multiple of the horizontal synchronizing signal frequency, thereby constructing the pilot signal generating means. Can be easy.

The reference clock for reading data from the memory 42 is a signal having a fixed frequency from the reference signal generator 58. The drum servo during VTR playback is
This is performed based on the output signal of the reference signal generator 58. The frequency divider 60 divides the read clock from the reference signal generator 58 into 1 / N. N = 52 for NTSC VTR
5 × 910 = 477750. Therefore, the frequency divider 60 supplies a pulse of about 30 Hz to the phase comparator 62. The drum motor rotates at about 30 Hz when the recording signal is NTSC, and the pulse PG indicating the rotation phase thereof is generated.
Is being output from the drum motor or rotating drum.
This pulse PG is shaped by the waveform shaper 61,
The above-mentioned switching signal having a duty ratio of 50% is generated. This switching signal, the pulse from the frequency divider 60 and the phase error are detected by the phase comparator 62, and the rotational phase of the drum motor 64 is controlled by the MDA (motor drive amplifier) 63. Although not shown, speed control is also performed in addition to this. With the above configuration, since the reproduced video signal is reproduced in synchronization with the reference signal generator 58, the average frequency of the write clock output from the VCO 49 following the jitter of the reproduced pilot signal is generated by the reference signal generator 58. The clock frequency becomes the same as that of the clock to be read, and the write address and the read address of the memory 42 cannot pass each other.

Conventionally, the phase comparison for generating the write clock was performed every fh, but in the present embodiment, 91 × fh.
Since phase comparison is performed 91 times in each horizontal period, that is,
The band in which jitter correction is possible can be significantly increased as compared with the conventional example. Next, a second embodiment of the magnetic recording / reproducing apparatus of the present invention will be described with reference to FIG. Second
The configuration of the recording system in the embodiment is the same as that of FIG. 1 described in the first embodiment, and the description will be omitted.

FIG. 4 is a block diagram showing the reproducing system of the second embodiment. In the first embodiment, the range in which phase comparison is possible is within ± 90 degrees of the phase of the pilot signal, and since the frequency of the pilot signal is approximately 1.4 MHz, approximately ± 350 n
Up to s. However, the time base fluctuation in the portion where the reproduction signals of the video head 11 and the video head 12 are switched by the switching signal may exceed this value. At this time, the device of the first embodiment can correctly respond to the jitter. become unable. Therefore, in FIG. 4, when the phase error between the horizontal synchronizing signal of the reproduced video signal and the signal obtained by dividing the output signal of the VCO 49 by 1/910 becomes larger than a predetermined value, this phase error is shown in FIG. It can add to the detected phase error and follow large jitter. Figure 4
3 is different from FIG. 3 in that reference numerals 70 to 77 constitute an adding means.

That is, the horizontal separation signal is separated from the reproduction luminance signal by the synchronization separation circuit 70. Also, VCO4
The output signal of 9 is divided into 1/910 by the frequency divider 72. Then, the phase error between the horizontal synchronizing signal and the output signal of the frequency divider 72 is obtained by the phase comparator 71. This phase error signal is band-limited by the LPF 73 and is switched by the switch 77.
Is supplied to. When the phase error signal has a level higher than the reference value V1, the output of the comparator 75 becomes high level, and when it is lower than the reference value V2, the output of the comparator 74 becomes high level. The high level outputs of the comparators 74 and 75 are controlled to close the switch 77 via the OR circuit 76. The phase error signal passed through the switch 77 is the phase error signal detected by the PLL circuit 46, that is, L.
The output of the PF 48 and the adder 78 are added. Therefore, when the amount of jitter of the reproduced video signal is within the predetermined range, the jitter is detected by the reproduced pilot signal, and when it exceeds the predetermined range, the jitter is also detected by the sync signal of the reproduced video signal. In this example,
The pull-in time of the PLL circuit 46 can be shortened even with respect to a large jitter that occurs when the reproducing head is switched, and the jitter can be corrected faithfully.

Next, a third embodiment of the magnetic recording / reproducing apparatus of the present invention will be described with reference to FIGS. 5 is a block diagram showing a recording system, FIG. 6 is a diagram showing a frequency spectrum of a recording signal, and FIG. 7 is a block diagram showing a reproducing system. As described above, the pilot signal has a relatively low frequency because it is recorded in the band between the low-frequency conversion carrier color signal 20 and the frequency-modulated luminance signal 21, so that the two video heads 11,
Even if the azimuth angles of 12 are different from each other, depending on the setting of the azimuth angle and the track width, the effect of reducing crosstalk due to azimuth loss may not be sufficiently obtained. When the reproduced pilot signal contains a crosstalk component from an adjacent track, the SN ratio of the pilot signal is deteriorated and the jitter detection accuracy is deteriorated. Therefore, in the third embodiment, the frequencies of the pilot signals recorded on the magnetic tape are made different between the adjacent fields so that the adjacent tracks have different frequencies, and the adjacent tracks on the magnetic tape are recorded. In order to reduce the influence of the crosstalk of the pilot signal of.

In FIG. 5, FIG. 1 described in the first embodiment is used.
6 is that a divider 82, a divider 83 and a switch 84 are provided instead of the divider 18. The frequency division ratio of the frequency divider 82 is 1 / m1, for example 1/91, and the frequency division ratio of the frequency divider 83 is 1 / m2, for example 1/70. The switch 84 includes a frequency divider 82 and a frequency divider 83 for each field of the video signal according to the switching signal supplied to the terminal 87.
Is switched and supplied to the phase comparator 15. Therefore, the VCO 17 has 91 fh (about 1.4
MHz) and 70 fh (about 1.1 MHZ) in frequency are alternately generated, which are frequency-multiplexed with the low-frequency conversion carrier color signal and the frequency-modulated luminance signal and recorded on the magnetic tape.

FIG. 6 shows the frequency spectrum of the recording signal. FIG. 6A shows the frequency spectrum of the recording signal of one field, and the frequency of the pilot signal 85 is about 1.4 MHz. FIG. 6B shows the frequency spectrum of the recording signal of the other field, and the pilot signal 8
The frequency of 6 is about 1.1 MHz.

Next, the reproducing system will be described. In FIG. 7, the BPF 101 and the BPF 102 are m from the reproduction signal.
1 × fh (= 91 × fh) and m2 × fh (= 70 ×
The pilot signals of the frequency fh) are separated.
The passband widths of these two BPFs are set so that the pilot signals reproduced as crosstalk from adjacent tracks are out of band. And switch 1
03 switches and outputs a pilot signal in accordance with a switching signal generated by the waveform shaper 61, and supplies the stabilized amplitude to the PLL circuit 104 by the AGC 44 and the limiter 45. The PLL circuit 104 changes the frequency division ratio for each field. That is, the frequency divider 105 divides the output signal of the VCO 49 into 1 / n1 such as 1/10, and the frequency divider 106
Divides the output signal of the VCO 49 into 1 / n2, for example 1/13. Then, in accordance with the above-mentioned switching signal, 91
When the track on which the pilot signal of × fh is recorded is being reproduced, the output of the frequency divider 105 is changed to the phase comparator 47.
The switch 107 is switched so that the output of the frequency divider 106 is supplied to the phase comparator 47 when the track on which the pilot signal of 70 × fh is recorded is reproduced. As a result, the PLL circuit 104 has a center frequency of 910 × fh in any field.
(= M × n × fh = m1 × n1 × fh = m2 × n2 × f
In h), it is possible to generate the write clock that follows the jitter of the reproduced pilot signal, that is, the jitter of the reproduced video signal. In the output signal of the phase comparator 47, the frequency of the signal for phase comparison differs depending on the field being reproduced, and thus the band of the detected jitter also differs. However, by limiting the band of the output of the phase comparator 47 by the LPF 48, the response characteristics of the PLL circuit 104 can be made the same between fields. Other configurations and operations are similar to those of the embodiment shown in FIG.

The frequency divider 82, the frequency divider 83 and the switch 103 shown in FIG. 5 or the frequency divider 105 and the frequency divider 10 shown in FIG.
6 and the switch 107 may each be configured by a programmable frequency divider to switch the frequency division ratio.

Next, a fourth embodiment of the present invention will be described with reference to FIG. Since the configuration of the recording system in the fourth embodiment is the same as that in FIG. 5 described in the third embodiment, the description will be omitted. BP that separates the pilot signal from the reproduced signal
The configurations of F101, BPF 102 and switch 103 are the same as those of the embodiment shown in FIG. Therefore, reproduced pilot signals having different frequencies for each field period are input to one input terminal of the phase comparator 47 of the PLL circuit 104. To the other input terminal of the phase comparator 47,
The outputs of the frequency divider 105 and the frequency divider 106 are switched and input for each field. The output of the phase comparator 47 is supplied to one input of the adder 78 through the LPF 48. The output of the adder 78 is fed back to the VCO 49, and the VCO 49 has an average frequency of 910 × fh that follows the jitter of the reproduced video signal in any field.
Output the clock.

To the other input of the adder 78, a horizontal synchronizing signal separated from the reproduction luminance signal and a signal obtained by dividing the output of the VCO 49 by 1/910 are provided as in the case of FIG. 4 described in the second embodiment. When the phase error of is larger than a predetermined value, the phase error is input.
Therefore, in the fourth embodiment, it is possible to reduce the influence of the crosstalk of the pilot signal from the adjacent track as in the second embodiment, and at the same time as when the reproducing head is switched, as in the third embodiment. It is possible to faithfully correct the jitter even for a large jitter.

Next, a fifth embodiment of the present invention will be described with reference to FIG. The present embodiment is different from the third or fourth embodiment in the structure of the multiplexing means and the generating means of the recording system. The other structure is the same as that of the third or fourth embodiment, and the description thereof is omitted.

In FIG. 9, the phase comparator 15, LPF1
6, a PLL circuit including the VCO 110 and the frequency divider 111 and frequency dividers 112a and 112b constitute a generating means, and the center frequency of the VCO 110 is 910 × fh. Therefore, the output signal of the VCO 110 has a frequency obtained by multiplying the frequency of the horizontal synchronizing signal by 910. VCO1
On the other hand, the output signal of 10 is divided by the frequency divider 112a into 1 / n
One frequency is divided into, for example, 1/10, and the other frequency is divided into 1 / n2, for example, 1/13 by the frequency divider 112b to generate two pilot signals. These pilot signals pass through BPF 19a and BPF 19b, respectively, and adder 6a.
And to the adder 6b. The adder 6a includes a frequency-modulated luminance signal, a low-frequency conversion carrier color signal, and a BPF.
The pilot signal from 19a is frequency-multiplexed and the multiplexed signal is supplied to the video head 11. Similarly, the adder 6b
Is frequency-multiplexed with the frequency-modulated luminance signal, the low-frequency conversion carrier color signal and the pilot signal from the BPF 19b,
The multiple signals are supplied to the video head 12. Therefore,
According to this structure, the frequency of the pilot signal does not switch within one track, and the pilot signals recorded on the magnetic tape are recorded at different frequencies between adjacent tracks.

In each of the embodiments described above, the case where the color signal is the carrier color signal in the NTSC television signal and the color signal is converted into the low frequency band by the frequency conversion is explained. The same can be done for PAL television signals. Further, also in a magnetic recording / reproducing apparatus that converts a frequency-modulated color signal such as a SECAM television signal into a low frequency band by frequency division, the band between the frequency-modulated luminance signal and the low-frequency band conversion color signal is similarly generated. Record the pilot signal in
It is possible to correct the time base fluctuation of the SECAM television signal reproduced based on the reproduction pilot signal. In the case of recording / reproducing a PAL system or SECAM system television signal, the frequency of each clock or the frequency division ratio of each frequency divider may be set to a value suitable for these signals.

[0033]

As described above, in the magnetic recording / reproducing apparatus of the present invention, in the band between the frequency-modulated luminance signal and the low frequency conversion color signal, an integer multiple of the horizontal synchronizing signal frequency of the video signal is generated. Since a pilot signal having a frequency is recorded and reproduced, the reproduced pilot signal is separated and the write clock of the time axis correction means is generated based on the reproduced pilot signal. This can be corrected by following the time-axis fluctuation including the spread and high frequency components. Further, since the pilot signal is recorded in the band between the frequency-modulated luminance signal and the low-frequency conversion color signal, even the conventional recording / reproducing apparatus or reproducing apparatus which does not record the pilot signal can be used in the magnetic recording / reproducing apparatus according to the present invention. The magnetic tape recorded in can be reproduced.

Further, when the detected value of the jitter due to the horizontal synchronizing signal of the reproduced video signal exceeds a predetermined range, this detected value is added to the detected value of the jitter due to the reproduced pilot signal, and the time axis correction means Since the write clock is generated, it is possible to widen the band in which the time axis fluctuation can be corrected, but it is possible to follow a large time axis fluctuation that occurs when the reproducing head is switched. it can. Further, the frequencies of the pilot signals recorded on the magnetic tape are made different between the adjacent tracks, and during reproduction, the division ratio of the PLL circuit for generating the write clock is switched according to the frequency of the reproduced pilot signals. With this configuration, it is possible to reduce the detection error of the time axis fluctuation component due to the crosstalk of the reproduced pilot signal from the adjacent track and improve the correction accuracy of the time axis fluctuation.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a recording system of a first embodiment of a magnetic recording / reproducing apparatus according to the present invention.

FIG. 2 is a diagram showing a frequency spectrum of a recording signal of the first embodiment of the magnetic recording / reproducing apparatus according to the present invention.

FIG. 3 is a configuration diagram showing a reproducing system of a first embodiment of a magnetic recording / reproducing apparatus according to the present invention.

FIG. 4 is a configuration diagram showing a reproducing system of a second embodiment of the magnetic recording / reproducing apparatus according to the present invention.

FIG. 5 is a configuration diagram showing a recording system of a third embodiment of the magnetic recording / reproducing apparatus according to the present invention.

FIG. 6 is a diagram showing a frequency spectrum of a recording signal of a third embodiment of the magnetic recording / reproducing apparatus according to the present invention.

FIG. 7 is a configuration diagram showing a reproducing system of a third embodiment of the magnetic recording / reproducing apparatus according to the present invention.

FIG. 8 is a configuration diagram showing a reproducing system of a fourth embodiment of the magnetic recording / reproducing apparatus according to the present invention.

FIG. 9 is a configuration diagram showing a recording system of a fifth embodiment of the magnetic recording / reproducing apparatus according to the present invention.

FIG. 10 is a configuration diagram showing a configuration of a time axis correction device used in a conventional magnetic recording / reproducing device.

[Explanation of symbols]

 6 adder (multiplexing means) 6a adder (multiplexing means) 6b adder (multiplexing means) 13 synchronization separation circuit 14 PLL circuit (generation means) 19 BPF 22 pilot signal 42 memory 43 BPF (separation means) 44 AGC 45 limiter 46 PLL circuit (write clock generation means) 47 phase comparator 48 LPF 49 VCO 50 frequency divider (first frequency divider) 51 memory control circuit 58 reference signal generator 70 synchronization separation circuit 71 phase comparator 72 frequency divider ( Second frequency divider) 73 LPF 74 Comparator 75 Comparator 76 OR circuit 77 Switch 78 Adder 82 Frequency divider 83 Frequency divider 101 BPF (separating means) 102 BPF (separating means) 103 Switch 104 PLL circuit (writing) Clock generation means) 105 frequency divider (first frequency divider) 106 frequency divider (first frequency divider) Divider) 107 switch 110 VCO 111 frequency divider 112a divider 112b divider V1 reference value (first predetermined value) V2 reference value (second predetermined value)

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[Procedure amendment]

[Submission date] November 1, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a recording system of a first embodiment of a magnetic recording / reproducing apparatus according to the present invention.

FIG. 2 is a diagram showing a frequency spectrum of a recording signal of the first embodiment of the magnetic recording / reproducing apparatus according to the present invention.

FIG. 3 is a configuration diagram showing a reproducing system of a first embodiment of a magnetic recording / reproducing apparatus according to the present invention.

FIG. 4 is a configuration diagram showing a reproducing system of a second embodiment of the magnetic recording / reproducing apparatus according to the present invention.

FIG. 5 is a configuration diagram showing a recording system of a third embodiment of the magnetic recording / reproducing apparatus according to the present invention.

FIG. 6 is a diagram showing a frequency spectrum of a recording signal of a third embodiment of the magnetic recording / reproducing apparatus according to the present invention.

FIG. 7 is a configuration diagram showing a reproducing system of a third embodiment of the magnetic recording / reproducing apparatus according to the present invention.

FIG. 8 is a configuration diagram showing a reproducing system of a fourth embodiment of the magnetic recording / reproducing apparatus according to the present invention.

FIG. 9 is a configuration diagram showing a recording system of a fifth embodiment of the magnetic recording / reproducing apparatus according to the present invention.

FIG. 10 is a configuration diagram showing a configuration of a time axis correction device used in a conventional magnetic recording / reproducing device.

[Description of Reference Signs] 6 adder (multiplexing means) 6a adder (multiplexing means) 6b adder (multiplexing means) 13 sync separation circuit 14 PLL circuit (generation means) 19 BPF 22 pilot signal 42 memory 43 BPF (separation means) 44 AGC 45 Limiter 46 PLL Circuit (Write Clock Generation Means) 47 Phase Comparator 48 LPF 49 VCO 50 Frequency Divider (First Frequency Divider) 51 Memory Control Circuit 58 Reference Signal Generator 70 Sync Separation Circuit 71 Phase Comparator 72 frequency divider (second frequency divider) 73 LPF 74 comparator 75 comparator 75 OR circuit 77 switch 78 adder 82 frequency divider 83 frequency divider 101 BPF (separation means) 102 BPF (separation means) 103 switch 104 PLL Circuit (Write Clock Generation Means) 105 Frequency Divider (First Frequency Divider) 106 Frequency divider (first frequency divider) 107 Switch 110 VCO 111 Frequency divider 112a Frequency divider 112b Frequency divider V1 Reference value (first predetermined value) V2 Reference value (second predetermined value)

Claims (3)

[Claims] 1. At the time of recording, a frequency-modulated luminance signal obtained by frequency-modulating a carrier with a luminance signal of a video signal and a low frequency band obtained by converting a color signal of the video signal into a lower frequency band of the frequency-modulated luminance signal. A recorded signal obtained by frequency-multiplexing the converted color signal is recorded on a recording medium by a rotary head, and at the time of reproduction, a reproduced frequency-modulated luminance signal frequency-separated from the reproduced signal from the recording medium is demodulated to reproduce a luminance signal. To obtain a reproduced video signal by converting the reproduced low-frequency converted color signal frequency-separated from the reproduced signal into the original frequency to obtain a reproduced video signal and correct the time base fluctuation of the reproduced video signal. In a magnetic recording / reproducing apparatus having a time axis correction means, a frequency that is an integer multiple of a horizontal synchronizing frequency of the video signal and that is between the frequency-modulated luminance signal and the low-frequency conversion color signal is set. Generating means for generating a recording pilot signal having; a multiplexing means for frequency-multiplexing the recording pilot signal with the frequency-modulated luminance signal and the low-frequency conversion color signal; and a separating means for separating a reproducing pilot signal from the reproducing signal. , A VCO and a first frequency divider for dividing the output signal of the VCO, and the oscillation of the VCO according to a first phase error signal between the reproduction pilot signal and the output signal of the first frequency divider. A magnetic recording / reproducing apparatus comprising: a write clock generating unit that controls a frequency to generate a write clock of the time axis correcting unit. 2. At the time of recording, a frequency-modulated luminance signal in which a carrier is frequency-modulated by a luminance signal of a video signal and a low frequency band obtained by converting a color signal of the video signal into a lower frequency band of the frequency-modulated luminance signal. A recorded signal obtained by frequency-multiplexing the converted color signal is recorded on a recording medium by a rotary head, and at the time of reproduction, a reproduced frequency-modulated luminance signal frequency-separated from the reproduced signal from the recording medium is demodulated to reproduce a luminance signal. To obtain a reproduced video signal by converting the reproduced low-frequency converted color signal frequency-separated from the reproduced signal into the original frequency to obtain a reproduced video signal and correct the time base fluctuation of the reproduced video signal. In a magnetic recording / reproducing apparatus having a time axis correction means, a frequency that is an integer multiple of a horizontal synchronizing frequency of the video signal and that is between the frequency-modulated luminance signal and the low-frequency conversion color signal is set. Generating means for generating a recording pilot signal having; a multiplexing means for frequency-multiplexing the recording pilot signal with the frequency-modulated luminance signal and the low-frequency conversion color signal; and a separating means for separating a reproducing pilot signal from the reproducing signal. , A VCO and a first frequency divider for dividing the output signal of the VCO, and the oscillation of the VCO according to a first phase error signal between the reproduction pilot signal and the output signal of the first frequency divider. Write clock generating means for controlling a frequency to generate a write clock for the time axis correcting means, a signal obtained by dividing the output signal of the VCO by a second divider, and a horizontal synchronizing signal separated from the reproduced video signal. And an addition means for adding the second phase error signal to the first phase error signal when the second phase error signal is greater than or equal to the first predetermined value and less than or equal to the second predetermined value. A magnetic recording / reproducing apparatus comprising: 3. The generating means generates the recording pilot signal so that adjacent tracks of tracks to be formed by scanning of the rotary head have different frequencies, and the write clock generating means causes the reproduction clock signal to be reproduced. Corresponding to different frequencies for each field period of the pilot signal, the first
3. The magnetic recording / reproducing apparatus according to claim 1, wherein the frequency division ratio of the frequency divider is switched.