JP3270884B2 - Magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus for eliminating chromo-macrostalk during reproduction and improving the S / N ratio.

[0002]

2. Description of the Related Art Conventionally, in a magnetic recording / reproducing apparatus (VTR), a CTR (C-comb filter + CNR circuit) shown in FIG. In the figure, C-com mainly consists of one NTS
C (1H) / PAL (2H) C comb filter composed of delay line 1, ATT (coefficient unit) and BPF
(Bandpass filter). The return route includes a chroma noise component and a crosstalk component from an adjacent track, and a chroma uncorrelated component. When the feedback loop is functioning by the switch SW, the S / N ratio can be improved by feeding back a noise component having a relatively small amplitude.

[0003]

However, since a crosstalk component having a large amplitude, that is, a chromo macrostalk component from an adjacent track is present in the feedback loop, a limiter circuit for extracting a noise component must be provided. And the amplitude cannot be limited so as to pass only noise. Therefore, if the amount of feedback is increased by increasing the value of ATT to improve the degree of improvement of the S / N ratio, more uncorrelated components are also fed back. In this case, color dripping is remarkably generated, and image quality is deteriorated.

In order to prevent the color drop, the switch SW may be switched by detecting the decorrelation of the Y signal so as to prevent the decorrelation portion of the chroma from being fed back. However, the Y signal and the chroma non-correlation part do not always coincide with each other, and there has been a problem that color dripping is conspicuous in the chroma non-correlation part where the Y signal non-correlation cannot be detected.
To suppress this image quality degradation, the feedback amount may be reduced, but this causes a problem that the degree of improvement of the S / N ratio is reduced, and both the reduction of color drop and the improvement and improvement of the S / N ratio are achieved. There was a problem that it became difficult.

Accordingly, an object of the present invention is to provide a magnetic recording / reproducing apparatus capable of preventing color sagging and improving the S / N ratio.

[0006]

To achieve the above object, a magnetic recording / reproducing apparatus according to the first aspect of the present invention comprises a C-comb filter comprising a C-comb filter and a feedback loop comprising a coefficient unit and a band-pass filter. A first path provided in the feedback loop and having a limiter circuit for limiting the amplitude of the feedback signal; and a feedback signal provided in parallel with the first path in the feedback loop. And a switching means for selectively switching whether the feedback signal is fed back through the first path or the second path in accordance with the presence or absence of crosstalk. It is characterized by having. In a preferred embodiment, when the switching unit does not include crosstalk, the switching unit feeds back the feedback signal through the first path and includes crosstalk, for example. The second
The feedback signal may be fed back through the path.

According to a third aspect of the present invention, there is provided a magnetic recording / reproducing apparatus having a C-comb comprising a C-comb filter and a feedback loop including a coefficient unit and a band-pass filter. A limiter circuit provided in the loop to limit the amplitude of the feedback signal,
A first path having a first attenuator having a first coefficient set therein, and a second attenuation provided in parallel with the first path in the feedback loop and having a second coefficient set therein. The first path according to the presence or absence of crosstalk,
And feedback means for adding the feedback signal passing through the second path and the feedback signal passing through the second path and feeding back the feedback signal passing only through the second path. Also,
In a preferred embodiment, the adding means is, for example, a fourth embodiment.
As described, when the crosstalk is not included, the feedback signals passing through the first path and the second path are added and fed back, while when the crosstalk is included, the second signal is added. The feedback signal may be fed back only through the path.

[0008]

According to the present invention, when the switching means does not include the crosstalk, the feedback signal is fed back through the first path having the limiter circuit. The feedback signal is fed back through the path without any signal processing. Therefore, depending on the presence or absence of crosstalk, it is possible to prevent color drop and to improve the S / N ratio.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a VRT reproduction chroma system according to an embodiment of the present invention. In the figure, reference numeral 10 denotes a color signal component amplitude automatic adjustment circuit (ACC: Automatic Chroma).
Control), and controls the amplitude of the color signal by comparing the amplitude of the color burst signal with the reference voltage. 11 is
12 is a PB converter, 12 is a band pass filter,
13 is a C-com. Reference numeral 14 denotes burst de-emphasis, which compresses a burst signal and restores the original amplitude. Reference numeral 15 denotes chroma de-emphasis, which compresses a chroma signal and restores the original amplitude. Reference numeral 16 denotes ACK. The present invention resides in the circuit configuration of the C-comb 13.

A-1. Next, FIG. 2 is a block diagram showing a configuration of a C-com according to the first embodiment. Parts corresponding to those in FIG. 4 are denoted by the same reference numerals, and description thereof is omitted. In FIG. 2, reference numeral 20 denotes a limiter, which removes uncorrelated chroma components from the output signal of the BPF 2. The switch SW1 selectively supplies the output signal from the limiter 20 to the ATT3 when the crosstalk is lower than the noise level, and selects the output signal from the BPF2 when the crosstalk is higher than the noise level. To ATT3. in this way,
In the first embodiment, a path (first path) via the limiter 20 and a path (second path) not via the limiter 20 are provided in the feedback loop of the VTR reproduction C-com. The switching operation of the switch SW1 is performed by a control signal CNT1 output from a control unit (not shown). That is, the control unit (not shown) detects the presence or absence of cross macrostalk, and according to the presence or absence, detects the control signals CNT and CNT.
CNT1 is output.

B-1. Operation of First Embodiment In the above-described configuration, the VTR mode (SP / LP,
(NTSC / PAL, etc.), the chroma may not include crosstalk, or even if it does, the noise level may be equal to or lower than the noise level. For example, the SAL of an 8 mm VTR PAL model with a head width of 27 microns
For P mode, the track width on the tape is 34 microns and there is a 7 micron guard band. In such a case, since the head rarely straddles the adjacent track, the crosstalk is lower than the noise level. In this case, the switch SW1 is switched to the limiter 20 to remove the chroma uncorrelated component. As a result, color dripping can be reduced. Further, even if the feedback amount is increased in order to improve the S / N ratio, the image quality can be improved without increasing color dripping. On the other hand, when the crosstalk is included, the light cannot pass through the limiter 20, so that by switching the switch SW1 to the other,
The output signal (feedback signal) from BPF2 is used as it is in ATT.
Supply to 3. As a result, the same performance as before can be obtained.

A-2. Next, FIG. 3 is a block diagram showing a configuration of a C-com according to the second embodiment. 4 or 2 are denoted by the same reference numerals and description thereof is omitted. 3, an attenuator (ATT) 21 attenuates the amplitude of an output signal from the limiter 20 and is supplied to one input terminal of an adder 23. 22 is the ATT21
Attenuator (AT) provided in another path (route)
T) and attenuates the amplitude of the output signal from BPF2,
The signal is supplied to the other input terminal of the adder 23. In the second embodiment, in the conventional circuit shown in FIG. 4, the improvement of the S / N ratio in the portion where the crosstalk is small due to the picture is improved. Thus, in the second embodiment, VT
A path (first path) via the limiter 20 and a path (second path) not via the limiter 20 are provided in the feedback loop of the R-reproduction C-com, and coefficients can be set independently for each path. ATTs 21 and 22 are provided.

B-2. Operation of the Second Embodiment In the above-described configuration, when no crosstalk is included in the chroma, a signal supplied through a path (path) formed by the limiter 20 and the ATT 21 and a signal of the ATT 22 The signal supplied via the path (path) is added by the adder 23, and this is fed back via the switch SW. As a result, the S / N ratio can be improved more than the conventional technology. On the other hand, when the chroma includes crosstalk, or in a non-correlated portion of the chroma, only the signal supplied via the path of the ATT 22 is fed back.
Therefore, in this case, the S / N ratio can be improved as in the conventional technique. As a result, the S / N ratio can be improved where the color on the screen is light and noise is conspicuous. It should be noted that the combination of the coefficients of ATT21 and ATT22 allows the S / N ratio improvement at a large amplitude and the S / N ratio improvement at a small amplitude at a noise level to be independently set. is there.

[0014]

According to the present invention, the first path having the limiter circuit for limiting the amplitude of the feedback signal and the second path which is provided in parallel with the first path and does not perform any signal processing on the feedback signal are provided. Are provided in a feedback loop, and either the first path or the second path is selectively formed as a feedback loop according to the presence or absence of chroma crosstalk. Therefore, the following effects can be obtained. . (1) Even if there is no or little crosstalk, color droop can be improved with the same amount of feedback as in the related art without impairing the degree of improvement in the S / N ratio. (2) Even if the S / N ratio is improved by increasing the feedback amount, the image quality is not degraded due to the color drop. (3) A path in which a limiter is inserted and a path without a limiter are provided, and the output of each path is coupled and decoupled by an adder, without switching the path.
It can respond to the presence or absence of crosstalk.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a VTR reproduction chroma system according to one embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a C-com according to the first embodiment.

FIG. 3 is a block diagram illustrating a configuration of a C-com according to a second embodiment.

FIG. 4 is a block diagram showing a configuration of a conventional C-com.

[Description of Signs] 20 Limiter 21 ATT (first attenuator) 22 ATT (second attenuator) 23 Adder (addition means) SW1 switch (switching means)

Claims (4)

(57) [Claims] 1. A magnetic recording / reproducing apparatus including a C-comb including a C-comb filter and a feedback loop including a coefficient unit and a band-pass filter, wherein the limiter is provided in the feedback loop and limits an amplitude of a feedback signal. A first path having a circuit, the feedback loop being provided in parallel with the first path;
Switching means for performing no signal processing on the feedback signal; and switching means for selectively switching whether the feedback signal is fed back through the first path or the second path in accordance with the presence or absence of crosstalk. And a magnetic recording / reproducing apparatus. 2. The switching means feeds back the feedback signal through the first path when crosstalk is not included, and switches the feedback signal through the second path when crosstalk is included. 2. The magnetic recording / reproducing apparatus according to claim 1, wherein a feedback signal is fed back. 3. A magnetic recording / reproducing apparatus having a C-com formed of a C-comb filter and a feedback loop including a coefficient unit and a band-pass filter, wherein the limiter is provided in the feedback loop and limits an amplitude of a feedback signal. A first path having a circuit and a first attenuator set with a first coefficient; and a feedback loop provided in parallel with the first path;
A second path having a second attenuator in which a second coefficient is set, and a feedback signal passing through the first path and the second path are added and fed back according to the presence or absence of crosstalk. On the other hand, a magnetic recording / reproducing apparatus comprising an adding means for feeding back a feedback signal passing only through the second path. 4. When the crosstalk is not included, the adding means adds a feedback signal passing through the first path and the feedback signal passing through the second path and feeds back the feedback signal. Wherein the feedback signal is fed back only through the second path.