JPS5853833B2 - recording/playback machine - Google Patents

Description

[Detailed description of the invention] A recording/reproducing machine that records video signals on a magnetic tape, the so-called V
Generally, as shown in FIG. 1, in a TR, two rotating magnetic heads HA and HB are installed with an angular spacing of 180°, and a tape 1 is wound diagonally around a tape guide drum 2 over an angular range of approximately 1800°. The heads HA and HB rotate once per frame, so that the heads HA and HB form diagonal tracks alternately for each field.

The running speed of the tape 1 is selected so that a so-called guard band is formed between the tracks formed by the heads HA and HB.

In such a recording/reproducing device, the amount of information that can be recorded on one tape is limited to about one hour, although this depends on the length of the tape and other factors.

However, programs such as movies and sports often last more than one hour, and when recording such programs, it is desirable to be able to record as long as possible on a tape of limited length.

One possible method for increasing the recording amount is to reduce the track width and therefore the width of the guard band.

However, in order to do this, it is necessary to reduce the gap width of the head, but with the current manufacturing technology, it is difficult to make the gap width much smaller than the conventional one.

For this reason, a method of recording without forming a guard band, that is, in such a way that each track is in contact with each other, can be considered.

When such a recording method is used, crosstalk from adjacent tracks becomes a problem during reproduction, and therefore it is required to eliminate or reduce this crosstalk by some method.

A method for solving this problem has already been proposed.

That is, as mentioned above, two rotating magnetic heads HA and HB
When using heads HA and H, as shown in FIG.
The angles of inclination of the gaps gA and gB of B with respect to the scanning direction shown by the arrow 3 are made to be different from each other.

Since video signals are generally recorded by angle modulation, for example, FM modulation, when the heads HA and HB are configured as described above, the track TA formed by the head HA and Even if the tape speed is selected to be slow so that the tracks TB formed by the head HB are in contact with each other, that is, there is no guard band,
During reproduction, crosstalk is significantly reduced due to the so-called azimuth loss due to the difference in slope of the gaps gA and gB between the heads HA and HB.

Therefore, since the track pitch can be reduced, the recording amount can be increased.

However, although this method is effective when the video signal is a black and white video signal, it is inconvenient when the video signal is a color video signal.

That is, when recording a color video signal, the luminance signal is generally angularly modulated, such as FM modulated, so that it occupies the high frequency side of the recordable band, and the carrier color signal is frequency converted so that it occupies the low frequency side. I am recording it.

Therefore, by configuring the heads HA and HB as described above,
When recording at high density as shown in Figure 3, the frequency of the luminance signal is raised, so the azimuth loss increases as described above and crosstalk decreases, but the carrier chrominance signal Since the frequency is kept low, azimuth losses are not increased and therefore crosstalk is not reduced.

In view of this point, the following method can be considered as a method for particularly reducing crosstalk of carrier color signals.

Conventionally, frequency conversion of a carrier color signal has been performed using a frequency conversion signal having a constant frequency and a constant phase.

On the other hand, in this method, during recording, the phase of the frequency conversion signal is advanced by 90' every horizontal section in the field where the track TA is formed, as shown in FIG.
In the field where the track TB is formed, the phase is delayed by 90° for each horizontal section.

Conversion of the carrier color signal to the original frequency during reproduction is also performed using a completely similar frequency conversion signal.

FIGS. 5 and 6 show the principle of this method.

That is, FIG. 5 shows the recording system, and numeral 38 is a frequency converter for converting the input carrier color signal to a low frequency range. A phase shifter 6B is used to advance the phase by 90 degrees to the contact point A, and a phase shifter 6B to advance the phase by 180 degrees to the contact point C.
A phase shifter 6D that advances the phase by 270° is connected to the contact point through C.
The signals switched by the switch 5 are supplied to the frequency converter 38 as a frequency conversion signal.

In the field where the track TA is formed, this switch 5 is switched in the order of contact A → contact B → contact C → contact D, contact A, etc. every horizontal section as shown by the solid arrow, and the track TA is In the field where TB is formed, on the contrary, as indicated by the broken line arrow, the switching is performed in the order of contact D → contact C → contact B → contact A → contact D, etc., every horizontal section.

39 is a low pass filter. FIG. 6 shows a reproduction system, and 92 is a frequency converter for returning the reproduced carrier color signal to its original frequency.
A signal with a constant frequency and a constant phase similar to that obtained in The signals are supplied through a phase shifter 9C that makes the phase advance, and a phase shifter 9D that makes the phase advance by 2700 to the contact point.The switch 8 is switched in the same manner as the switch 5 during recording, and the switched signal is used as a signal for frequency conversion. It is supplied to a frequency converter 92.

The output of the frequency converter 92 is extracted through a bandpass filter 93 and a so-called C-shaped comb filter 95 .

When this method is used, even when high-density recording is performed without forming guard bands between tracks as shown in FIG. 3, the crosstalk of the carrier color signal is reduced to a substantially negligible level during reproduction.

Let me explain why.

ωS If the carrier frequency of the original carrier color signal is fs=- and 2π, the original carrier color signal recorded on the track TA is sin[ωst + θ] in any n-th horizontal section.・・・・・・・・・(
1-1), and in the next n+1 horizontal interval, s
in CO3 (t + 7) + θA) ””-・(
21), respectively.

However, τ is one horizontal period.

Similarly, as shown in FIG. 7, the original conveyed color signal recorded on the track TB is recorded in the m-th horizontal section adjacent to the recording position of the n-th horizontal section of the track TA. , and the next <that is, the recording position is n + of track TA
The (m+1)th horizontal section adjacent to the recording position of the first horizontal section is expressed as follows.

and the frequency supplied to the frequency converter 38 in the field in which the track TA is recorded.

Since the phase of the π conversion signal advances by 90, that is, - in each horizontal interval, the frequency conversion signal is as follows in the n-th horizontal interval, and in the next n + 1-th horizontal interval, , respectively.

Of course, ωC>ωS. Similarly, trough, riTB
In the field in which is recorded, the phase of the frequency conversion signal supplied to the frequency converter 38 is delayed by 90 degrees, that is, by - for each horizontal section, so that the frequency conversion signal is delayed by 90 degrees for each horizontal section. Then, in the next (m+1)th horizontal interval, it is expressed as .

Therefore, in the n-th horizontal section, the low-frequency converted carrier color signal actually recorded on the track TA is the product of the signal expressed by equation (1-1) and the signal expressed by equation (1-2). Among those obtained as , the angular frequency is ωL=ωC−
ωS, which is expressed as: In the next n+1 horizontal interval, (2−
Of those found as the product of the signal expressed by equation 1) and the signal expressed by equation (2-2), the angular frequency is ωL=
ωC−ωS, which is expressed as follows.

Similarly, the low-band converted carrier color signal actually recorded on the track TB is (3-1
) and the signal expressed by equation (3-2), of which the angular frequency is ω, = ω
C-ωS, which is expressed as (4-1
) of the signal expressed by equation (4-2) and the signal expressed by equation (4-2), the angular frequency is ω□=ω
C-ωS, which is expressed as follows.

FIG. 7 shows the recorded signals.

In the case where the track TA is reproduced during reproduction, in the field where the track TA is reproduced, the phase of the frequency conversion signal supplied to the frequency converter 92 is the same as during recording. Since the phase advances by 90 degrees, that is, by - in each section, the frequency conversion signal is, in the horizontal section where the signal of the nth horizontal section is reproduced, In the horizontal section where the signal is reproduced, each is represented by .

In this case, when the head HA reproduces the signal of the n-th horizontal section of the track TA, the head HA simultaneously reproduces the signal of the n-th horizontal section of the track TA.
Since the signal in the m-th horizontal section of is obtained as crosstalk, the signal extracted from the filter 93 in the n-th horizontal section is the signal expressed by equation (1-3) and (1-4).
The main signal whose angular frequency is ωS, which is obtained as the product of the signals expressed by the equation, is obtained as the product of the signal expressed by the equation (3-3) and the signal expressed by the equation (1-4). This is the sum of the crosstalk components whose angular frequency is ωS.

Similarly, when the head HA reproduces the signal of the n+1-th horizontal section of the track TA, it simultaneously receives the signal of the m+1-th horizontal section of the adjacent track TB as crosstalk. The signal extracted from the filter 93 in the section is the main signal whose angular frequency is ωS, which is obtained as the product of the signal expressed by equation (2-3) and the signal expressed by equation (2-4), and , (4-3) and the signal expressed by equation (2-4), which is the sum of the crosstalk components whose angular frequency is ωS.

Then, in the C-shaped comb filter 95, the output signal of the filter 93 one horizontal period before is subtracted from the output signal of the filter 93 at that time, so that an arbitrary (n+1)th horizontal section in which the track TA is reproduced. The carrier color signal finally obtained from the comb filter 95 is expressed as follows.

Here, the carrier frequency fs of the original carrier color signal is 3,58
ME(z is chosen to have a one-line offset relationship, and if the horizontal frequency is fH, then there is the relationship, so , and , and .

Therefore, becomes.

That is, in the comb filter 95, the adjacent track T
Crosstalk components from B are canceled out.

In this way, by phase-shifting the frequency conversion signal as described at the beginning and inserting the C-shaped comb filter 95 in the reproduction system, the Talostalk of the carrier color signal is eliminated.

Thus, according to the above-mentioned special method, it is possible to eliminate the crosstalk of the carrier color signals.

Therefore, even when recording a color video signal, it is possible to record with high density, and the recording time can be greatly increased compared to the conventional method.

In the method described above, switching the switches 5 and 8;
That is, the phase of the frequency conversion signal is switched by, for example, a switching signal obtained based on a signal for identifying the track T person and TB obtained from pulses indicating the rotational angular positions of the heads HA and HB, and a horizontal synchronization signal. The switching of the switch 5 during recording and the switching of the switch 8 during reproduction maintain a synchronous relationship, so that the phase of the frequency conversion signal during recording matches the phase of the frequency conversion signal during reproduction.

In addition, the reproduction system is equipped with a so-called APC circuit, similar to a normal recording/reproducing machine, which compares the phase of the burst signal in the carrier color signal obtained from the comb filter 95 with the reference signal from the reference oscillator. The phase of the signal applied to terminal 7 is controlled by the comparison error voltage.

Therefore, in equations (5M) and (6M), (k−n
)-=01 φ-αA=0, and the comb filter 9
It is assumed that the phase of the reproduced carrier color signal obtained in step 5 matches the original carrier color signal, that is, the carrier color signal supplied to the frequency converter 38 at the time of recording.

Figures 8A to 8D show this relationship, where A indicates the horizontal synchronization signal during recording, B indicates the phase of the frequency conversion signal during recording, and C indicates the horizontal synchronization signal during playback. , D indicate the phase of the frequency conversion signal during reproduction, respectively.

By the way, during playback, the horizontal synchronization signal may be missing due to dropout or the like, or a pseudo horizontal synchronization signal may be generated due to noise.

If this happens, the switching phase of the switch 8 will be out of order, and the frequency conversion signal will no longer be phase-shifted in a normal relationship.

For example, if one horizontal synchronization signal is missing as shown in figure E,
As shown in F of the same figure, the phase of the frequency conversion signal is 90° out of the correct phase, and as shown in G of the same figure, the phase of the carrier wave of the reproduced carrier color signal is 90° there, assuming that the correct phase is Oo. It shifts.

In addition, if two horizontal synchronization signals are missing in a row as shown in H in the figure, or two pseudo horizontal synchronization signals occur within the same horizontal interval as in the figure, the frequency will change as shown in ■ or L in the figure. The phase of the conversion signal is eventually 180° with respect to the correct phase.
As shown in J or M in the figure, the phase of the carrier wave of the reproduced carrier color signal also deviates by 180 degrees from the correct phase.

By the way, as mentioned above, there is an APC circuit in the reproduction system, and when the phase of the frequency conversion signal is correct, the phase comparison circuit of the APC circuit compares the phase between the burst signal vB in the reproduced carrier color signal and the reference signal. V.

are in a 90' relationship with each other as shown in FIG. 9, and no error voltage is generated.

When the phase of the carrier wave of the reproduced carrier color signal is shifted by 90° from the correct phase as described above, the burst signal vB and the reference signal Vo mentioned above are in phase with each other or out of phase with each other as shown in FIG. , and a positive or negative error voltage is generated.

Therefore, in this case, if the response characteristics of the APC circuit are fast, the phase of the signal applied to the terminal 7 will be corrected in a relatively short time, that is, the phase of the frequency conversion signal will be set to the correct phase, and there will be no special inconvenience. Does not occur.

However, the phase of the carrier wave of the reproduced carrier color signal is 180° with respect to the correct phase as shown in Figure 8J or M.
When the deviation occurs, the above-mentioned burst signal vB and reference signal ■o
As shown in FIG. 11, they are in a 90° relationship with each other, and no error voltage is generated.

Therefore, at this time, even if the response characteristic of the APC circuit is fast, it takes a considerable amount of time until the phase of the signal applied to the terminal 7 is corrected and the phase of the frequency conversion signal is set to the correct phase.

Therefore, during this period, the hue of the reproduced image is disturbed, which is an inconvenience.

The present invention is designed to avoid such inconveniences with a simple configuration.

In the present invention, as described above, when the phase of the carrier wave of the reproduced carrier color signal is deviated by 180° from the correct phase, the phase of the reproduced carrier color signal is inverted by the phase detection output of the burst signal in the reproduced carrier color signal.

Hereinafter, the recording/reproducing apparatus according to the present invention will be explained in detail.

FIG. 12 shows an example of the overall circuit configuration of a recording/reproducing apparatus according to the present invention, where 11 is an input terminal for a color video signal to be recorded, and 12 is an output terminal for a reproduced color video signal.

HA and HB are rotating magnetic heads, which are separated by an angular interval of 1800 as shown in FIG. 1. For example, as shown in FIG. 2, the inclinations of the respective gaps gA and gB are made different from each other.

Reference numerals 13 to 17 indicate recording/reproduction changeover switches, which are respectively switched to the contact R side during recording and switched to the contact P side during playback.

Reference numeral 1B denotes a pulse generator, which is provided in relation to the rotational axes of the heads HA and HB, and is capable of obtaining frame period pulses at predetermined rotational angular positions of the heads HA and HB.

First, let's explain the case of recording.

The color video signal from the input terminal 11 is passed through the low-pass filter 2.
0 and extracts the luminance signal, which is sent to the AGC
The signal is supplied through the circuit 21 and through the contact R side of the switch 13 to a so-called Y-shaped comb filter 22 .

That is, the filter 22 includes a delay circuit 19 having a delay time of one horizontal period and an adder 23, from which a luminance signal from which subcarrier components have been removed is obtained.

This luminance signal is sequentially supplied to an FM modulator 28 through a subcarrier trap circuit 24, a clamp circuit 25, a pre-emphasis circuit 26, and a clip circuit 27, where it is FM modulated, and the modulated luminance signal is passed through a bypass filter 29.
It is supplied to the synthesizer 40 through.

The color video signal from the input terminal 11 is also supplied to a bandpass filter 30 to extract a carrier color signal, which is supplied to a frequency converter 3B through an AGC circuit 31 and frequency-converted to the lower frequency side.

This frequency conversion is performed using a frequency conversion signal whose phase is shifted as described above.

The carrier frequency f3 (=3.58MHz) of the original carrier color signal
) is selected as shown in equation (8), and when frequency converting this carrier color signal to the lower frequency side, the carrier frequency fL of the converted carrier color signal is generally selected based on the relationship of -line offset. For example,

Therefore, fO is Frequency of signal for frequency conversion It is said that there is a relationship between

In the example in the figure, if such a relationship is chosen,
50 is a so-called AFC circuit for forming a signal with a frequency of 44fH, and 55 is (227+-)f
This is a so-called APC circuit for forming an H frequency signal.

That is, in the AFC circuit 50, the oscillation center frequency is 4.
The oscillator number of the 4fH variable frequency oscillator 51 is the frequency divider 52.
Furthermore, the luminance signal from the AGC circuit 21 is supplied to the horizontal synchronizing signal separation circuit 53 to extract the horizontal synchronizing signal, and the phase comparator circuit 54 separates the luminance signal from this horizontal synchronizing signal. The output signals of the frequency generator 52 are phase-compared, and the variable frequency oscillator 51 is controlled by the comparison error voltage, thereby obtaining a signal with a frequency of 44 fH.

On the other hand, the APC circuit 55 has a variable frequency oscillator 56 whose oscillation center frequency ■ is (227+ -)fH and a reference oscillator 57 whose oscillation frequency is fixed at fs, The signal is supplied to a burst gate circuit 58 and a burst signal is taken out.
The phases of this burst signal and the oscillation signal of the reference oscillator 57 are compared in the phase comparison circuit 59, and the variable frequency oscillator 56 is controlled by the comparison error voltage.
7+-)fH frequency signal is obtained.

In the example shown in the figure, the phase of the 44fH frequency signal obtained from the AFC circuit 50 is shifted by 90° every horizontal interval, so that the phase of the final frequency conversion signal is also shifted by 90' every horizontal interval. This is the case when

That is, 4 from the variable frequency oscillator 51 of the AFC circuit 50
A phase shifter 121B causes a signal with a frequency of 4fH to pass through the contact A of the switch 120 as it is and advance the phase by 90' to the contact B.
A phase shifter 121C that advances the phase by 180 is connected to the contact C through the
A phase shifter 121 is provided to advance the phase by 270° at the contact point.
Each is supplied through D.

On the other hand, the frame period pulses obtained from the pulse generator 18 are supplied to the track discrimination signal forming circuit 64, and the state is reversed between the field where the head HA should form the track TA and the field where the head HB should form the track TB. This pulse signal and the horizontal synchronizing signal obtained from the horizontal synchronizing signal separation circuit 53 are supplied to the switching signal forming circuit 65.

The switching signal obtained from the switching signal forming circuit 65 is then supplied to the switch 120, and the switch 120 is switched in the same manner as the switching of the switch 5 described above.

A signal obtained from this switch 120 with a frequency of 4 4 fH and whose phase is shifted by 90° every horizontal section is supplied to the frequency converter 61 through the switch 123 of the phase correction circuit 122, and is also supplied to the variable frequency oscillator of the APC circuit 55. A signal with a frequency of (227+-)fa obtained from 56 is supplied to a frequency converter 61, from which
) is expressed by the formula.

, and the phase is shifted by 90 degrees every horizontal section, that is, in the field where the track TA is formed, the phase advances by 900 every horizontal section, and in the field where the track TB is formed, the phase shifts by 90 degrees every horizontal section. A frequency conversion signal whose phase is delayed by 90 degrees is obtained.

This frequency conversion signal is passed through the bandpass filter 62.
The carrier color signal is supplied to the frequency converter 38 through the frequency converter 38, and the carrier color signal is frequency-converted to the lower frequency side, that is, so that the carrier frequency becomes fL:fc-f3 described above.

Therefore, as the frequency conversion signal is phase-shifted, the phase of the carrier wave of the frequency fL of this low-frequency converted carrier color signal is also shifted in phase, as described above.

This carrier color signal is supplied to a synthesizer 40 through a low pass filter 39.

Then, a composite signal of the FM-modulated luminance signal and the carrier color signal that has been low-frequency converted using the special method described above, obtained from the synthesizer 40, is supplied to the heads HA and HB via the recording amplifier 41. Track TA as shown in Figure 3
and high-density recording with no guard band formed between the TB and TB.

In FIG. 3, PH is the recording position of the horizontal synchronizing signal, whose center is arranged on a straight line perpendicular to the extending direction of the tracks TA and TB, as shown by the broken line in the figure.

Next, let's talk about playback.

During reproduction, tracking servo is applied so that the head HA scans the track TA and the head HB scans the track TB, as in a normal recording/reproducing machine.

The playback output of heads HA and HB is provided by a playback amplifier 71.
and 72 to the switches 73 and 74, and the pulse signal obtained from the track discrimination signal forming circuit 64 described above turns on the switch 73 in the field where the head HA reproduces the track TA, and the head HB reproduces the track TB. In the field where the signal is input, the switch 74 is turned on, and the reproduced signals obtained from both switches 73 and 74 are combined by a combiner 75.

This synthesized reproduction signal is supplied to a bypass filter 80 to extract an FM-modulated luminance signal, which is supplied to an FM demodulator 82 through a limiter 81 and demodulated, and the demodulated luminance signal passes through a low-pass filter 83. The signal is supplied to the synthesizer 100 through a de-emphasis circuit 84.

The synthesized reproduced signal is also supplied to a low-pass filter 90 to extract a carrier color signal that has been low-pass converted using a special method as described above, and is supplied to a frequency converter 92 through an ACC circuit 91. converted to the original frequency.

This frequency conversion is performed using a frequency conversion signal whose phase is shifted as in the case of recording.

That is, the reproduced luminance signal obtained from the de-emphasis circuit 84 is supplied to the horizontal synchronization signal separation circuit 53, while the carrier color signal at the original frequency obtained from a C-shaped comb filter 95 (described later) is supplied to the burst gate circuit 58. The switch 120 is switched in the same manner as the switch 8 described above, and the phase is shifted from the frequency converter 61 through the bandpass filter 62 in the same manner as in the case of recording, that is, the track TA is reproduced. 1 in the field
A frequency-converted signal is obtained that advances in phase by 90' in each horizontal section and lags in phase by 90° in each horizontal section in the field in which track TB is reproduced, and this is supplied to the frequency converter 92 to convert the carrier color signal. is frequency-converted to the original frequency, that is, the carrier frequency becomes f3=fc-fl.

The carrier color signal returned to its original frequency is supplied to a C-shaped comb filter 95 through a bandpass filter 93.

The filter 95 is composed of the above-mentioned delay circuit 19 having a delay time of one horizontal period and a subtracter 96.
The carrier color signals from 5 are provided to a combiner 100.

A reproduced color video signal is then outputted to the output terminal 12.

On the other hand, a phase detection circuit 125 separate from the phase comparator circuit 59 of the APC circuit 55 is provided, and a burst signal vB in the reproduced carrier color signal obtained from the burst gate circuit 5B is supplied to this phase detection circuit 125. The reference signal ■o from the oscillator 57 is supplied to the phase shifter 126 and the signal 90'
The phase is shifted to another reference signal (2), which is supplied to a phase detection circuit 125, the output of the phase detection circuit 125 is supplied to a flip-flop circuit 127, and the output of this flip-flop circuit 127 is used as a switching signal to switch 123.
supplied to

During playback, the switch 120 is correctly switched in synchronization with the time of recording, and the phase of the frequency conversion signal supplied to the frequency converter 92 is changed to the phase of the frequency converter 38 during recording.
When the phase matches the phase of the frequency conversion signal supplied to the burst gate circuit 5, as explained in FIG.
The burst signal vB obtained from the reference oscillator 57 and the reference signal Vo obtained from the reference oscillator 57 maintain a phase difference of 90', and for example, the burst signal vB is delayed in phase by 90'.

Therefore, if the phase is delayed by 90 degrees in the phase shifter 126, then the reference signal (2) obtained from the phase shifter 126 and the burst signal vB have an in-phase relationship as shown in the figure. Therefore, the phase detection circuit 125 does not generate a trigger signal for inverting the flip-flop circuit 127.

As mentioned above, during playback, the horizontal synchronization signal is missing or a pseudo horizontal synchronization signal is generated due to noise, and as shown in FIG.
When the deviation is 0°, as explained in Fig. 10, the reference signal Vo and the burst signal vB are in the same phase or in opposite phase, and therefore the reference signal Vx and the burst signal vB are as shown in the figure. , 900.

Therefore, at this time as well, the phase detection circuit 125 does not generate a trigger signal for inverting the flip-flop circuit 127.

On the other hand, during playback, the horizontal synchronization signal may be missing or a pseudo horizontal synchronization signal may occur due to noise, causing the
When the phase of the frequency conversion signal deviates from the correct phase by 180 degrees as shown in FIG. 11, the reference signal Vo and the burst signal vB have a phase difference of 90' as explained in FIG. Contrary to when the phase of the frequency conversion signal is correct, the phase of the burst signal vB is advanced by 90'.

Therefore, at this time, the reference signal Vx and the burst signal vB have an opposite phase relationship as shown in the figure, and a negative signal is obtained from the phase detection circuit 125, which is supplied as a trigger signal to the flip-flop circuit 127. and its output is inverted.

Therefore, in the phase correction circuit 122, the switch 123
If it had been switched to the contact a side until then, it is switched to the contact side, and the signal with a frequency of 4 4 fH obtained from the switch 120 is sent to the phase inversion circuit 124.
The phase of the signal is inverted and supplied to the frequency converter 61.

Therefore, the phase of the frequency conversion signal supplied to the frequency converter 92 is also inverted and corrected as shown by the broken line in FIG. , which is the correct phase.

When the same condition occurs again, the switch 123 is switched from the contact side to the contact a side, and the same correction is made.

Therefore, with such a configuration, the hue of the reproduced image will not be disturbed for a long time as described above.

A phase correction circuit 122 consisting of a switch 123 and a phase inversion circuit 124 includes a switch 120 and phase shifters 121B and 12
It may be provided on the front side of the phase switching circuit 128 consisting of 1C and 121D, or on the output side of the variable frequency oscillator 56 of the APC circuit 55, before or after the bandpass filter 62, or on the frequency converter 92, the filter 93 or 9
It may be provided before or after 5.

In the above example, the AFC circuit 50 obtains a signal with a constant phase of 44 fH, and the phase switching circuit 128 shifts the phase by 90' for each horizontal section. The same thing can be done even if a logic circuit such as a so-called lead-on memory is configured such that a signal having a frequency of 44 fH and whose phase is shifted by 90 degrees per horizontal interval is directly obtained.

FIG. 13 shows an example of this case, where the lead-on memo IJ-
130, the horizontal synchronizing signal PH (FIG. 15A) from the horizontal synchronizing signal separation circuit 53 is supplied to the frequency divider 131, and the signal at the frequency of -fH is supplied to the frequency divider 131.
No. 2 P■ (B in the same figure)
is obtained, which is further fed to the frequency divider 132 to
A signal P with a frequency of fH.

(C in the same figure) is obtained, and the horizontal synchronization signal PH is
A phase-locked circuit with a similar configuration to the PC circuit 50, so-called PL
A signal PK (
D) in the same figure is obtained, and this is supplied to the one-frequency divider 134 to obtain a signal PL of 44fH (E in the same figure). A pulse signal PF (F in the figure) whose state is inverted between the field for forming or reproducing the track TA and the field for forming or reproducing the track TB obtained from the pulse signal PF 64 is supplied to the read-on memory 130.

As a result, the read-on memory 130 receives 44 fH.
, and the phase is shifted by 90' for each horizontal section, that is, in the field corresponding to track TA, the phase advances by 90° for each horizontal section, and in the field corresponding to track TB, the phase is shifted by 90' for each horizontal section. Signal Ps whose phase is delayed by 90°
(FIG. 15G) is formed.

Therefore, in this example, this lead-on memo IJ-
The signal Ps obtained from the switch 130 may be supplied to the frequency converter 61 through the phase correction circuit 122 instead of the output signal of the switch 120 in the example shown in FIG.

When a lead-on memory or the like is used in this way, it is also possible to configure the device without providing the phase correction circuit 122 consisting of the switch 123 and the phase inversion circuit 124.

That is, in the example of FIG. 13, the lead-on memory 130 is 5
However, as shown in the example of FIG. 14, this is configured as a six-manpower type, and the output of the above-mentioned flip-flop circuit 127 is also connected to the lead-on memory IJ-130.
so that the phase of the output signal of the memory 130 is also determined by the state of the output of the flip-flop circuit 127, i.e. when the output of the circuit 127 is "O" and "
1", the phase of the output signal of the memory l-130 may be inverted.

Due to the above-described configuration, the phase of the signal obtained from the variable frequency oscillator 56 of the APC circuit 55 changes to 90% for each horizontal section.
The frequency conversion signals supplied to the frequency converters 38 to 92 may be shifted in phase by 10 degrees, or the frequency conversion signals supplied to the frequency converters 38 to 92 may be directly phase shifted, as shown in principle in FIGS. good.

Furthermore, instead of the frequency conversion signal being phase-shifted in the end, a phase-shifting circuit may be inserted before or after the frequency converters 38 and 92 to directly phase-shift the carrier color signal. The present invention can also be applied to this case.

The slopes of the gaps gA and gB of the heads HA and HB do not need to be different.

That is, the following method can also be taken as a countermeasure against the crosstalk of the luminance signal.

During recording, for example, by changing the DC bias in the FM modulator 28 between the field in which the track TA is formed and the field in which the track TB is formed, the brightness signal can be adjusted to the straight line 1 in FIG.
41, and the track TB is deviated by (l+-)fH (l=0.1.
2. ...) FM modulation is performed according to the characteristics shown by the straight line 142.

Therefore, the modulation frequencies are in a frequency interleaved relationship between the tracks TA and TB, and the crosstalk components during playback are inverted in phase between adjacent horizontal sections, and the crosstalk of the luminance signal is They are visually offset and become less noticeable on the playback screen.

As described above, according to the present invention, when high-density recording is performed by reducing the crosstalk of the carrier color signal using a special method, the hue of the reproduced image will not be disturbed for a long time.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an example of a rotating magnetic head mechanism of a recording/reproducing machine, Fig. 2 is a diagram showing an example of the state of the magnetic gap of the rotating magnetic head, and Fig. 3 is an example of a recording pattern on a tape. Figures 4 and 4 are diagrams for explaining the recording and reproducing method that is the premise of the present invention, Figures 5 and 6 are diagrams showing the basic configuration of the recording system and reproducing system in this method, and Figure 7 is a diagram for explaining the recording and reproducing method that is the premise of the present invention. FIGS. 8 to 11 are diagrams for explaining the state of recording signals when using this method, and FIGS.
2 to 14 are system diagrams of an example of a recording/reproducing apparatus according to the present invention, and FIGS. 15 and 16 are diagrams for explaining the same. 38. 61 and 92 are frequency converters, 50 is an AFC circuit, 53 is a horizontal synchronizing signal separation circuit, 55 is an APC circuit, 5
7 is a reference oscillator, 58 is a burst gate circuit, 64 is a track discrimination signal forming circuit, 95 is a C-shaped comb filter,
128 is a phase switching circuit, 122 is a phase correction circuit, 124
125 is a phase detection circuit, 126 is a phase shifter, 127 is a flip-flop circuit, and 130 is a lead-on memory.

Claims (1)

[Claims] 1. A human-powered carrier color signal is converted into a carrier color signal in which the phase of the carrier wave is shifted by 90' in a predetermined direction for each horizontal section, and the recorded medium is reproduced. By performing a phase shift operation for each horizontal section, a reproduced carrier color signal in which the phase of the carrier wave is constant is obtained, and a burst signal in the reproduced carrier color signal is phase-detected, and the detection output is used to detect the phase of the burst signal in the reproduced carrier color signal. , because the phase shift state in the recorded carrier color signal and the phase shift operation in the reproduction system do not have a normal correspondence, the phase of the carrier of the reproduced carrier color signal is the same as the phase of the carrier of the input carrier color signal. A recording/reproducing apparatus detects a deviation of 180 degrees from the original color signal, and inverts the phase of the reproduced conveyance color signal when this is detected.