JPS59231989A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To eliminate beat disturbance due to crosstalk component by changing a center frquency of an angular modulating circuit at each unit period to allow an unnecessary component in a reproduced line sequential chrominance signal to enter a blocking band of a comb line filter. CONSTITUTION:The frequency of the beat component at the center carrier is f-f', where (f) is the center carrier frequency of the angular modulation line sequential chrominance signal recorded on a prescribed track and f' is that of an adjacent track. The said frequency is selected to a frequency corresponding to a trough of the characteristic of the comb line filter 28. Thus, the carrier frequency of the angular modulating circuit 10 in the recording system is made different by the frequency at the trough of the filter 28 every time a track is formed on a magentic tape 18. As a result, the frequency offset is applied to the angular modulation line sequential chrominance signal between adjacent tracks and the beat component is eliminated by the filter 28 of the reproducing system.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a magnetic recording and reproducing device suitable for recording and reproducing color video signals using an azimuth recording method, and in particular, the present invention relates to a magnetic recording and reproducing device suitable for recording and reproducing color video signals using an azimuth recording method. The present invention relates to a magnetic recording/reproducing device that sets a frequency band lower than that of a modulated luminance signal.

[Background of the invention]

Conventionally, one of the important issues for magnetic recording and reproducing devices that record and reproduce color video signals is to improve the recording density and lengthen the magnetic tape recording time, especially because of the need to spread them to general households. For this reason, it was necessary to reduce the running speed of the magnetic tape while maintaining a good reproduced image. In this way, when the running speed of the magnetic tape is slowed down, the recordable band of the magnetic tape is naturally narrowed, and the standard color video signal, in which the frequency band of the color signal is set on the high frequency side, can be used as is. If recorded and reproduced in this format, the color signal will deteriorate and it will not be possible to obtain a high quality color reproduced image.

Therefore, in order to solve this problem, the luminance signal is angularly modulated and set on the high frequency side, and the color signal is set on the low frequency side and recorded on the magnetic tape. In order to record a color video signal in a standard format, for example, the NTSC format, the color video signal is divided into a luminance signal and a chroma signal, and the luminance signal is divided into a luminance signal with a center frequency of approximately 4 MHz.
Along with angle modulation using the z carrier wave, the chroma signal is frequency-converted to the lower frequency side, and the respective signals are mixed and recorded.

FIG. 1 is a spectrum diagram showing the frequency bands of the angle-modulated luminance signal and the low-band converted chroma signal when the color video signal is recorded as described above, where 1 is the low-band converted chroma signal; 2 is a carrier wave of the angle-modulated luminance signal, and 3 is a sideband wave of the angle-modulated luminance signal.

When the color video signal recorded in this manner is reproduced, the angle-modulated luminance signal is distorted, and the chroma signal is converted to the original frequency.

These signals are mixed into a standard color video signal and supplied to a color television receiver.

The same applies to the color video signal of the 5ECAId system, and the color video signal is a line-sequential color signal (hereinafter referred to as angle-modulated) consisting of a luminance signal and two angle-modulated color difference signals (R-y) and (B-y). The luminance signal is angle-modulated using a carrier wave with a center frequency of about 4.5 MHz, and the angle-modulated line-sequential color signal is frequency-converted to the lower frequency side.

The respective signals are mixed and recorded.

FIG. 2 is a spectrum diagram showing the frequency bands of the angle-modulated luminance signal and the angle-modulated line-sequential color signal that has been low-band converted when a color video signal of the 5ECAI11 system is recorded as described above, where 4 is the angle Modulation line sequential color signal carrier wave,
5 is the sideband wave of the angle modulation line sequential color signal, and 2.3 is
These are the carrier wave and sideband wave of the angle-modulated luminance signal, respectively, as in FIG.

During reproduction, the angle-modulated luminance signal is intensified, and the angle-modulated line-sequential color signal is converted to its original frequency and restored to a SECAM color video signal.

In this way, even if the running speed of the magnetic tape is slowed down and the recordable band of the magnetic tape is narrowed.

Although it has become possible to reproduce the colors of reproduced images, in order to further improve the recording density, a so-called azimuth recording method is adopted, and guard bands are not provided between tracks on the magnetic tape.

This makes the magnetization direction different between adjacent tracks on a magnetic tape, and by reproducing and scanning these tracks with a magnetic head with an azimuth angle that matches the magnetization direction, even if tracking deviation occurs, the magnetic head Since the signal is reproduced only from the track whose magnetization direction matches the azimuth angle, the guard band provided in consideration of tracking deviation becomes unnecessary.

Therefore, by adopting such an azimuth recording method, it has become possible to further vary the running speed of the magnetic tape, and it has become possible to lengthen the recording time.

As described above, in conventional magnetic recording and reproducing devices, it has become possible to significantly extend one recording time6, but on the other hand, the image quality of reproduced images has been affected.

In particular, there were problems with color reproducibility.

That is, in a magnetic recording and reproducing apparatus, jitter occurs in the reproduced signal due to uneven running of the magnetic tape, uneven rotation of the magnetic head, and the like. The jitter greatly affects the quality of the reproduced image.

In particular, when a chroma signal is obtained by quadrature two-phase balanced modulation of a carrier wave using two color difference signals, such as an NTSC color video signal, this chroma signal contains color information with a different phase. If the phase of the chroma signal is affected by jitter, the color difference signal from the chroma signal will not be accurately captured, and the color reproducibility of the reproduced image will deteriorate, resulting in discoloration of one image, or in the worst case scenario. The color does not appear on one image (sometimes there are eight cases).

Therefore, in order to prevent such deterioration of color reproducibility, when converting the reproduced chroma signal to the original frequency, the chroma signal is frequency-converted using a signal that contains the same jitter as the chroma signal, and the chroma signal is included in the chroma signal. 61-However, in order to form a signal that includes the same jitter as the chroma signal, a high-precision automatic frequency control circuit and automatic phase control circuit are all required, making the single circuit configuration complicated. Not only is it expensive.

Since the jitter present in the horizontal synchronization signal and colorverse signal period is used to cancel out the jitter of the chroma signal for each horizontal period, it is not possible to completely eliminate the jitter within one horizontal period, and the reproduced image Color shift will remain. In particular, in high-definition television systems, which require even higher image quality than the current NTSC system, the tolerance for one color shift is tighter than the current system, which causes even more jitter. Although it is necessary to eliminate the influence of

On the other hand, in the SECAM system color video signal, since the line-sequential color signal is angle-modulated, one color information is represented by a frequency, and the frequency of the carrier wave is sufficient compared to the jitter frequency. Since the frequency is large, even if the angle modulation line sequential color signal fluctuates in frequency due to jitter, the amount of frequency fluctuation relative to the frequency of the carrier wave is almost negligible. From this, when magnetically recording and reproducing color video signals, d.

By using an angle modulation line sequential color signal, it is not affected by jitter and has excellent color reproducibility of reproduced images, and there is no need to install a special circuit in the color signal processing system to remove jitter. In particular, it is very suitable for television systems that require high image quality, such as high-definition television systems.

In this way, when recording and reproducing with the frequency band of the luminance signal set to the high side and the frequency band of the color signal set to the low side, this color signal is angularly modulated a! Sequential color signals have the excellent feature of being able to avoid the shadow of jitter 4111, but on the other hand, a new problem arises in that crosstalk from adjacent tracks occurs, and this causes problems in the reproduced image. This results in deterioration of image quality.

That is, as mentioned above, the azimuth recording method is adopted in the magnetic recording/reproducing apparatus to eliminate guard bands between adjacent tracks. However, although this azimuth recording method is effective for high-frequency recording signals, it is not sufficiently effective for low-frequency angle-modulated line-sequential color signals. Therefore, if the magnetic head causes tracking deviation and simultaneously reproduces and scans not only a predetermined track but also a part of the adjacent track, the reproduction signal from the magnetic head - the angle modulation line sequentially reproduced from this predetermined track Not only the signals but also the angle modulation line sequential color signals (hereinafter referred to as crosstalk components) are reproduced and mixed in, although the amplitude is small, from the adjacent tracks. Therefore, as shown in FIG. The signal is obtained by adding a crosstalk component 6, which also consists of the carrier wave and sideband waves, to the angle modulated line sequential color signal reproduced from the above-mentioned predetermined track, which consists of the carrier wave 4 and sideband waves 5.

These two signals were recorded on two adjacent tracks, but their frequencies are slightly different from each other, and when these mixed signals are supplied to the wandering circuit, due to their non-linearity, A beat will occur. This beat component is visible on the playback screen and deteriorates the quality of the playback image.

As described above, in conventional magnetic recording and reproducing devices that employ the azimuth recording method, by recording color signals sequentially in one hue number and all angle modulation lines, the influence of jitter can be eliminated, and image quality deterioration due to this jitter can be eliminated. However, recording color signals in this manner caused a new problem of crosstalk, and it was still not possible to obtain a reproduced image of good quality.

[Purpose of the invention]

The object of the present invention is to eliminate the drawbacks of the above-mentioned prior art.

When the azimuth recording method is adopted and the 16 signals are mixed with the angle modulated luminance signal in the high frequency band as the 111i primary color signal (low frequency band angle modulated line) and recorded and reproduced, beat interference due to crosstalk components from adjacent tracks is avoided. An object of the present invention is to provide a magnetic recording and reproducing device that can remove the magnetic particles and obtain high-quality reproduced images.

[Summary of the invention]

In order to achieve this objective, the present invention is characterized in that the carrier frequency of the angle-modulated line-sequential color signal is different between adjacent tracks, and the beat component to be mixed into the reproduced and demodulated line-sequential color signal is the line-sequential color signal. and remove the beat component with a comb-shaped filter that utilizes the correlation of 2Hc (where H is the horizontal period),
Moreover, the characteristics of the comb-shaped filter are changed according to the correlation between the 2Bs of the line-sequential color signals, and the deterioration of resolution caused by the comb-shaped filter can also be prevented. .

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 (αL (b+) is a block diagram showing an embodiment of the magnetic recording/reproducing apparatus according to the present invention, in which α1 indicates a recording system, and (bl indicates a reproduction system).

7 is an input terminal, B is a dynamic emphasis circuit, 9
1 is a pre-emphasis circuit, 10 is an angle modulation circuit, 11 is an input terminal, 12 is an addition circuit, 16 is an input terminal, 14 is a processing circuit, 15 is an angle modulation circuit, 16 is a recording amplifier circuit, 1
7 is a magnetic head, 18 is a magnetic tape, 19 is a preamplifier circuit, and 20 is a full band.

21 is a low-pass filter; 22. i is an angle modulation circuit, 24°25 is a low-pass filter, 26 is a processing circuit, 27 is a de-emphasis circuit, 2B is a comb filter, 29 is a delay device, 60 is a subtraction circuit, 31 is an IJ transmitter, 32 is a subtraction circuit , 33 is a dynamic de-emphasis circuit, 34.
55 is an output terminal.

First, the recording system shown in Figure 4) will be explained.

From the input terminal 7, a line-sequential color signal formed by a well-known means (however, the line-sequential signal of two combined signals is also included)
is supplied, and a luminance signal is supplied from the - input terminal 13.

The line sequential color signal is supplied to a dynamic emphasis circuit 8. The dynamic emphasis circuit 8 has a characteristic that the amount of emphasis varies depending on the level of the input signal, and that it gives greater emphasis to input signals of small amplitude. For this reason, the small amplitude portion of the line sequential color signal is more emphasized.

Next, the line sequential color signal is supplied to a pre-emphasis circuit 9 to further emphasize its high frequency components.

The signal is supplied to the angle modulation circuit 10. The angle modulation circuit 10 is
For example, it is a one-frequency modulation circuit, and the center carrier frequency is periodically changed by a control signal supplied from the input terminal 11. Therefore, an angle-modulated line-sequential color signal whose central carrier frequency changes periodically, ie, an angle-modulated line-sequential color signal, is obtained. The frequency V spectrum of this angle-modulated line-sequential color signal shifts by one frequency by two in the frequency axis direction as the center carrier frequency changes.

On the other hand, the luminance signal supplied from the input terminal 13 is supplied to a processing circuit 14 where it is subjected to predetermined processing such as clamping, and then to an angle modulation circuit (for example, one frequency modulation circuit).
15 for angle modulation.

This angle-modulated luminance signal, that is, the angle-modulated luminance signal and the angle-modulated line-sequential color signal from the angle modulation circuit 1o are mixed in the mixing circuit 12, amplified in the recording amplifier circuit 16, and supplied to the magnetic head 17. and recorded on the magnetic tape 18.

In this case, the center carrier frequency of the angle modulation circuit 10.15 is set so that the frequency band of the angle modulation line sequential color signal is on the low side, and the frequency band of the angle modulation luminance signal is on the high side. It is set. Although the magnetic head 17 is illustrated as one magnetic head, it is actually two magnetic heads with different azimuth angles, and azimuth recording is performed on the magnetic tape 18 without a guard band. There is.

Next, the reproduction system shown in FIG. 4 (bl) will be explained.

The magnetic head 17 reproduces and scans each track on the magnetic tape 18 to reproduce a mixed signal of the angle-modulated luminance signal and the angle-modulated line-sequential color signal. This mixed signal is amplified by a preamplifier circuit 19, and is passed through a bandpass filter 20 and a low-pass filter 21.
and will be supplied.

Bandpass filter 20 separates the angle modulated luminance signal from the mixed signal. This angle-modulated luminance signal is modulated by an angle demodulation circuit (for example, 1 frequency 07/1 circuit) 22 to obtain a luminance signal, and this luminance signal is supplied to a low-pass filter 24 to remove mixed carrier waves, etc. Unnecessary components are removed, predetermined processing such as clamping is performed in the processing circuit 26, and the signal is supplied to the output terminal 34. On the other hand, the low-pass filter 21 separates the angle-modulated line-sequential color signal from the mixed signal. This angle-modulated line sequential color signal is transmitted to an angle demodulation circuit (for example, a frequency demodulation circuit) 25.
The color signal is then adjusted to create a line-sequential color signal.

A low-pass filter 25 removes unnecessary components from the carrier waves, and the carrier waves are supplied to a de-emphasis circuit 27 . De-emphasis circuit 27 hub-emphasis circuit 9 (Fig. 4 (al)
The pre-emphasis circuit 9 suppresses the high-frequency components of the line-sequential color signal emphasized by the pre-emphasis circuit 9. These pre-emphasis circuit 9 and de-emphasis circuit 27 improve the S/IN of high frequency components with a small imaging width.

The line sequential color signal from the de-emphasis circuit 27 is supplied to a comb filter 28.

The comb-shaped filter 28 converts the line-sequential color signal into 2H (however, H
is delayed by one horizontal period). for example.

Delay device 29, such as a semiconductor delay device such as a ccn (charge coupled device). A subtraction circuit 30 that subtracts the line sequential color signal delayed by 2H in the delay device 29 from the delayed strong line sequential color signal, and an IJ to which the difference signal from the subtraction circuit 30 is supplied.
Mitter 31. Limiter 3 from undelayed line sequential color signal
It consists of a subtraction circuit 32 that subtracts the difference signal from 1.

In the comb-shaped filter 28 having such a configuration, if the supplied line sequential color signal is S, then this line sequential color signal S is delayed by 2H in the delay device 29. ``This delayed line sequential color signal SD is supplied to the subtraction circuit 60 together with the line sequential color signal S, and subjected to subtraction processing to obtain a difference signal Δ5 (=S-SD). This difference signal ΔS is the difference between portions of the line sequential color signal S separated by 2H.

In other words, color signals every 1H forming line-sequential color signals (
Alternatively, it represents the difference between 2H of color difference signals).

This difference signal ΔS is supplied to a limiter 61.

The limiter 31 acts so that the level of the output signal is constant for input signals with a high level, and changes the level of the output signal for input signals with a low level, and an example of its characteristics is as follows. is shown in Figure 5. In this example, when the input level is large from 0 dB to 1') to O dB, the output level is constant at 26 dB, and when the single power level is 120 dB or less, the gain is 16 dB.
It is dB.

The difference signal ΔS is the value of the limiter 31, α・ΔS (however,
α is the ratio of the input amplitude to the output amplitude, 0 × α<1)
Then, by subtracting the output signals α and ΔS of the IJ transmitter 31 from the undelayed line-sequential color signal S by the subtraction circuit 32, the output signal of the comb-shaped filter 28 becomes:

S-α·Δ5-(1-α)S+αφsD.

Therefore, from FIG. 5, it is assumed that the difference signal ΔS from the subtraction circuit 3o has a large amplitude of QtdB.

Since the output level is 126 dB, the input/output amplitude ratio is α multiplied by 1/20'''C, so the output signal of the comb filter 28 is given by the above equation.

1π5+-9-5D. In addition, when the difference signal ΔS is -20 dB, which is a small imaging width, the input/output amplitude ratio α is ((-26) - (-20)
)dB=-6dB, which is 1/2, so the output signal of the comb filter 28 is.

S ten SD 2 becomes.

From the above, the comb-shaped filter 28 becomes more effective as the difference between 2H of the line-sequential color signals becomes larger.

The more the correlation between 2Hs disappears, the smaller the contribution of the 2H-delayed line-sequential color signal becomes, allowing the line-sequential color signal that is not delayed to pass through. The contribution of the delayed line-sequential color signal is large, and the signal averaged over 2H of the line-sequential color signal becomes the output signal of the comb-shaped filter 28. Therefore 1. As shown in FIG. 6, the frequency characteristics of the comb-shaped filter 28 are flatter as the correlation between 2Hs of the line sequential color signals is lower, and as the correlation is higher, as shown in FIG.

When the frequency is fy/2, the peaks are the same, and when by/4+ftt/2, the peaks are troughs, exhibiting a comb-shaped characteristic. However, rL=0.1.2...
; fH is the repetition frequency V of the horizontal synchronizing signal.

Therefore, by utilizing this comb-shaped characteristic, beat components that are mixed into the reproduced line-sequential color signal due to crosstalk from adjacent tracks of the magnetic tape 18 are removed. As mentioned earlier, this beat component is due to the nonlinearity of the angle demodulation circuit 23.

This is caused by the beat between the angle modulated line sequential color signal reproduced from a predetermined track and the crosstalk from the track adjacent to this predetermined track.
If the center carrier frequency of the angle modulation line sequential color signal recorded on the above-mentioned predetermined track is f, and the center carrier frequency of the angle modulation line sequential color signal recorded on the adjacent track is f', then the beat of these center carrier waves is The frequency of the component is f-f
' becomes. Therefore, this frequency is
As long as the frequency corresponds to the valley of the characteristic of 8 < + f
What is necessary is to set it to H/4+n·ht/2.

In order to set the frequency of the beat component in this way, the fourth
(In α1, the carrier frequency of the angle modulation circuit 10 is
Every time a track is formed on the magnetic tape 18 by the control signal from the input terminal 11,
only different. As a result, a frequency offset of f74+le·fp/2 is applied to the angle-modulated line sequential color signal between adjacent tracks, and as described above, the beat component is is removed.

By the way, if the correlation between 2H of the line-sequential color signal is low, the frequency characteristics of the comb-shaped filter 28 become flat, so that the beat component cannot be removed. However, where the correlation is low, the beat component is less noticeable,
In this case, if the signal components corresponding to the valleys are removed due to the comb-shaped characteristic, the color resolution in the vertical direction is reduced.

Therefore, when the correlation is low, the comb filter 28
By flattening the frequency characteristics, deterioration of color resolution in the vertical direction is prevented.

FIG. 4 (Returning to Al, the line sequential color signal from the comb filter 28 is transferred to the dynamic de-emphasis circuit 36.
supplied to Dyna S Wakudy Emphasis Circuit 63
has a characteristic opposite to that of the dynamic emphasis circuit 8 (FIG. 4 (α)), and suppresses the small amplitude portion of the line-sequential color signal emphasized by the dynamic emphasis circuit 8. therefore.

The dynamic emphasis circuit 8 and the dynamic de-emphasis circuit 33 improve the S/N of the small amplitude portion of the line sequential color signal. The line sequential color signal processed in this way is supplied to the output terminal 35.

As described above, when the azimuth recording method without the guard band is adopted, even if beat components are mixed into the reproduced line-sequential color-sequential color signal due to crosstalk from adjacent tracks.

This beat component can be removed without deteriorating the image quality of the reproduced image, and a reproduced image with improved image quality and good one-color reproducibility can be obtained without deteriorating the color resolution in the vertical direction.

In the above embodiment, by providing the low-pass filter 25 before the de-emphasis circuit 27, the dynamic range of the subsequent circuit can be effectively utilized; however, the present invention is not limited to this; The filter 25 may be provided after the de-emphasis circuit 27. Further, in the above embodiment, the de-emphasis circuit 2
7 in front of the comb-shaped filter 28.

Although de-emphasis is applied to the high-frequency components of the line-sequential color signal and the dynamic range of the subsequent circuit can be effectively utilized, the present invention is not limited to this, and the de-emphasis circuit 27 can be replaced with a comb-shaped filter. It may be provided at a stage subsequent to 28. Further, in the embodiment described above, the dynamic de-emphasis circuit 63 is provided after the de-emphasis circuit 27, so that dynamic de-emphasis can be accurately applied to the high frequency components of the line-sequential color signal. Furthermore, one invention ICf, -
In this case, a dynamic de-emphasis circuit 35 is provided after the comb-shaped filter 28 to suppress small amplitude distortion components generated in the comb-shaped filter 28, but the present invention is not limited to this. Without.

The dynamic emphasis circuit 33 is connected to the comb filter 2.
It may be provided before B.

Furthermore, in the comb filter 28, the subtraction circuit 30 may subtract the undelayed line j@next color signal S from the delayed line sequential color signal SD from the delay device 29. In this case, it is necessary to use an addition circuit in place of the subtraction circuit 32.

Furthermore, as shown in FIG.
In this case, a high-pass filter 36 may be provided after the limiter 31 so that the comb-shaped characteristic of the comb-shaped filter 28 is applied to the high-frequency components of the line-sequential color signal. Alternatively, a bandpass filter may be used in place of the high-pass filter 36. This improves horizontal color resolution.

In this embodiment, in order to further suppress beat interference due to crosstalk, horizontal synchronization signal recording sections are arranged between adjacent tracks.

In addition to the ``°H arrangement'', it is desirable that the same type of color signals or color difference signals be arranged in a so-called 6-color arrangement.

Furthermore, the phase of the carrier wave of the angle modulation circuit 10 is inverted every 2H, and the leak component of the carrier wave mixed into the line-sequential color signal is suppressed by the comb-shaped filter 28. This is because this leak component is inverted every 2H, so the subtraction circuit 29 of the comb-shaped filter 28 detects this leak component, and the subtraction circuit 62 detects the leak component included in the line-sequential color signal that is not delayed. This is because the leakage components are offset by the leakage components. Further, instead of inverting the phase of the carrier wave every 2H, the phase of the carrier wave may be shifted by 90 degrees every 1H. As a result, the order of the low-pass filter 25 can be set low, and it is also possible to reduce the phase fluctuation of the color signal and obtain a high-quality reproduced image. However, in this case, a phase lock loop is provided in the angle modulation circuit 10 in order to lock the phase of the angle modulation line sequential color signal to a predetermined phase as described above for each starting point of each H.

Furthermore, since the carrier frequency of the angle modulation circuit 10 is varied by J'JF/ every 2H, the beat component due to the leakage component of the carrier wave of the angle modulation line sequential color signal is
It is interleaved every 21 on the playback screen and is visually reduced. In this case, the value of the offset of the carrier wave is 4
It will be repeated 0°0, frt/2, fn/2 for every H, but O-fry/4, every 4H.
Even if fH/2 and -fry/4 are used, the offset value for every 2H is fH/2, and the same effect can be obtained.

Above, modifications, other examples of operation, effects, etc. of the embodiment shown in FIG. It is.

FIG. 8 is a block diagram showing the main parts of another embodiment of the magnetic recording and reproducing apparatus according to the present invention, in which 37 is a dropout detection circuit, 38 is a changeover switch, and the part corresponding to 1hI in FIG. are given the same reference numerals and some explanations will be omitted.

In this embodiment, a compensation signal is obtained by the delay device of the comb-shaped filter 28, and dropout compensation can be performed. A selector switch 3 is connected between the comb filter 28 and the dynamic de-emphasis circuit 53.
8 is provided, and the output signal of the comb filter 28 and the output signal of the delay device 29 of the comb filter 28 are switched and supplied to the dynamic emphasis circuit 36. The angle-modulated color signal from the low-pass filter 21 (FIG. 4(bl)) is supplied to a dropout detection circuit 37, and the changeover switch 38 is controlled by the output signal of this dropout detection circuit 67.

Next, the operation of this embodiment will be explained.

When there is no dropout, the changeover switch 38 is closed to the contact A side, and the output signal of the comb filter 2B is supplied to the dynamic de-emphasis circuit 35. This is the same operation as the Al regeneration system shown in FIG.

When a dropout occurs in the reproduced signal, the dropout detection circuit 37 detects this dropout and closes the changeover switch 3B to the contact B side.

For this purpose, the delay device 29 delays the line-sequential color signal by 21, that is, the line-sequential color signal output by the comb filter 28 is delayed by 21.
H The preceding line-sequential color signal is the compensation) signal,
The signal is supplied to a dynamic de-emphasis circuit 36.

Therefore, the dropout period is compensated for by a 2H preceding homogeneous color signal.

In this way, the dropout of the 16 signals is compensated for, and the color reproducibility of the reproduced image is further improved.

FIG. 9 is a block diagram showing a modified example of FIG. 8,
38' is a changeover switch, and parts corresponding to those in FIG. 8 are given the same reference numerals.

In this modification, a changeover switch 68' is provided on the front plate of the comb-shaped filter 28, and it is possible to compensate for a dropout of -2H or more.

When there is no dropout, the selector switch 38' is closed to the contact A side, and the line sequential signal from the de-emphasis circuit 27 is transferred to the line sequential signal from the de-emphasis circuit 27 as shown in FIG.
The signal is supplied to a dynamic emphasis circuit 63 through a comb filter 28 which operates in the same manner as I.

On the other hand, when there is a dropout, the changeover switch 38' closes to the contact B side, and the output signal of the delay device 29 is again supplied to the delay device 29 via the changeover switch 68', and at the same time, the subtraction circuit ! Also provided on 10.32. Because in this case the two signals supplied to the subtraction circuit are the same.

The difference signal output by the subtraction circuit 50 is always zero.

Therefore, the subtraction circuit 32 is supplied with only the signal passed through the changeover switch 38, and the output signal of the comb filter 28 is a line sequential signal delayed by 2H from the delay device 25. This is supplied to the dynamic de-emphasis circuit 33. Changeover switch 38' is connected
, As long as it is closed to the B side, the line sequential color signal is delayed by the delay device 2.
9 and a selector switch 38', and this circulating line-sequential color signal is supplied to a dynamic de-emphasis circuit 36. Therefore, dropouts of 2H or more are compensated for with the same type of color signal.

In this modification, dropout detection is performed using modulation line sequential color signals, but the changeover switch 38
The demodulated line-sequential chrominance signal may be used as long as it is a signal before being supplied to .

Further, when a dropout occurs, the operation for removing the beat disturbance is not performed, but since the dropout is about pH at most, the beat disturbance is visually negligible.

FIG. 10 is a block diagram showing another modification of the one shown in FIG. A switch 38' is provided.

The operation of this modification is that when there is no dropout, the changeover switches 38 and 38' are closed to the contact A side, and the line-sequential color signals from the de-emphasis circuit 27 are transferred to the comb-shaped filter 2.
8 and is processed by the dynamic de-emphasis circuit 33.
However, when a dropout is detected, the changeover switch 38, 38' closes to the contact B side, and the line sequential color signal delayed by 2H from the delay device 29 of the comb filter 28 is supplied as a compensation signal. The signal is supplied to a dynamic de-emphasis circuit 53.

At the same time, the changeover switch 38, 38' changes to contact B.
As long as the delay device 29 is closed to the side, the line-sequential color signal from the delay device 29 is supplied to the delay device 29 again via the changeover switch 38' to compensate for dropouts over 2H.

In this variant, the dropout period comb filter 2
The output signal of 8 is sent to the dynamic de-emphasis circuit 36.
Since the output signal of the changeover switch 68' is not supplied to the subtraction circuit! Instead of using the input signal of 10.32, the output signal of the de-emphasis circuit 27 may be used as the input signal of the subtraction circuit 30.52.

FIG. 11 is a block diagram showing a modification of FIG. 9. In FIG. 9, when there is no dropout, delay device 2
When the signal obtained by subtracting the output signal of the high-pass filter 36 from the input signal of 90 drops out, the output signal of the high-pass filter 3B is zero, and only the input signal of the delay device 29 is input to the subtraction circuit. 62 to the dynamic de-emphasis circuit 53, but in this modified example shown in FIG. At times, the contact A is closed to output the output signal of the subtraction circuit 32, and during the dropout period, the contact B is closed to output the input signal of the delay device 290 to 1.
The signal is supplied to a dynamic emphasis circuit 66.

In this modification, the output signal of the comb filter 28 is supplied to the dynamic de-emphasis circuit 63 when there is no dropout.

Delay device 29 of comb filter 28 during dropout
The output signal is supplied as a compensation signal to the dynamic de-emphasis circuit 33 via the changeover switch 38', and at the same time is supplied again to the delay device 29 to compensate for dropout over 2H.

Above, we have described several modifications that enable dropout compensation in the present invention. In this way, it is possible to form a compensation signal using a delay device of a comb-shaped filter and compensate for dropout. be.

As mentioned earlier, since the luminance signal, line-sequential color signal, and Fi are recorded on the same track, dropouts occur in these signals at the same time. [7 Therefore, when compensating for the dropout of the luminance signal, the dropout detection circuit 57 (the eighth
11) can also be used. Additionally, instead of the angle-modulated line-sequential color signal from the low-pass filter 21, the dropout detection circuit 37 receives the angle-modulated luminance signal and angle-modulated line-sequential signal from the preamplifier circuit 19 (FIG. 4(h)). A signal mixed with a chrominance signal may be supplied, or an angle-modulated luminance signal separated by a bandpass filter 20 (FIG. 4 (hl)) may be supplied.

Further, the delay device 29 used in the comb-shaped filter 28 may be a semiconductor delay device such as a CCD or the like, but it may also be an ultrasonic delay device formed from a glass delay element, etc. In this case, the delay device 29 may be It is clear that the frequency V@ range of the line-sequential color signal to be passed must be converted in consideration of the child's passable band.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to prevent beat interference due to crosstalk from adjacent tracks, and also to prevent deterioration of resolution, which greatly improves the color reproducibility of reproduced images. However, by adopting the azimuth recording method and eliminating the guard band, it is possible to realize high-quality reproduced images during high-density recording. A recording/playback device can be provided.

[Brief explanation of the drawing]

Fig. 1 is a spectrum diagram showing the frequency bands of the angle-modulated luminance signal and the low frequency converted chroma signal in a conventional magnetic recording/reproducing device, and Fig. 2 is a spectrum diagram showing the frequency band of the angle-modulated luminance signal and the low-frequency converted chroma signal in a conventional 5ECAId type magnetic recording/reproducing device. FIG. 3 is a spectrum diagram showing the frequency band of the angle modulation line sequential chrominance signal that has undergone low frequency conversion; FIG. 3 is an explanatory diagram showing the influence of crosstalk from adjacent tracks on the angle modulation line 11th chrominance signal; FIG. 4 (αl, (AI shows one embodiment of the magnetic recording/reproducing device according to the present invention, FIG. 4 (α) is a block diagram showing a recording system, FIG. The figures are as shown in Figure 4 (input/output characteristic diagram of the limiter in the AI comb filter, Figure 6 is the frequency characteristic diagram of the limiter in the AI comb filter, and Figure 7 is the input/output characteristic diagram of the limiter in the AI comb filter. FIG. 8 is a block diagram showing another embodiment of the magnetic recording/reproducing apparatus according to the present invention, and FIGS. 9, 10, and 11 are the same as those in FIG. It is a block diagram showing a modified example. 7... Input terminal for line sequential color signal 10... Angle modulation circuit 11... Input terminal for control signal 12... Addition circuit 13... Input of luminance signal Terminal 15...Angle modulation circuit 20...Band filter 21...Low pass filter 2λ2!1...Angle demodulation circuit 28...Comb filter 29...Delay device 60...Subtraction circuit 31 ...Limiter 3
2... Subtraction circuit 64... Output terminal for luminance signal 35... Output terminal for line-sequential color signal 36... High-pass filter patent attorney Akio Takahashi

Claims (1)

[Claims] In a magnetic recording/reproducing device that mixes an angle-modulated luminance signal in a high frequency band and an angle-modulated line-sequential color signal in a low frequency band, and performs azimuth recording by widening guard bands between adjacent tracks, the line-sequential color signal is is supplied to the angle modulation circuit which generates all the angle modulated line sequential color signals and whose center frequency is variable, and the reproduced and modulated line sequential color signal is supplied to the 2H of the line sequential color signal (however, H is A comb-shaped filter whose pass characteristics change according to the correlation between the two horizontal periods) is provided, and the center frequency of the angle modulation circuit changes every unit period, so that the line-sequential color signal that is reproduced has a A magnetic recording/reproducing device characterized in that the unnecessary component to be mixed has a frequency spectrum in the blocking region of the comb-shaped filter.