JPS6139796A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent the deterioration of a reproduced picture due to mixing of a luminance signal to a chrominance signal by detecting the vertical correlation of the chrominance signal and limiting a recording or reproducing band of the luminance signal when the vertical correlation is weaker than the prescribed value. CONSTITUTION:A Y signal (b) and a C signal (g) are separated from an input signal (a) by a comb-shaped filter 2. On the other hand, the input signal (a) and a component of 3.58MHz of 1H delayed signal pass through BPFs 25 and 24 to turn out to be signals (c) and (d), respectively, and transmitted to a comparator 26. It compares the amplitude or phase of the signal (c) with those of the signal (d), and generates the signal in accordance with the difference. A band limiting circuit 27 inputs a signal (e), and limits the band of the Y signal at a high level. The band limiting circuit 27 is composed of an LPF or band obstructing filter. Namely, when the signal (e) is at a high level, the Y signal band is limited, and the Y signal (b) becomes a Y signal (f), whereby noises never occur. This can be obtained in a reproduction system of a VTR.

Description

DETAILED DESCRIPTION OF THE INVENTION 2. Field of Vane Industrial Application The present invention relates to a magnetic recording/reproducing apparatus such as a video tape recorder using a carrier color signal low frequency conversion recording method.

Conventional Structures and Their Problems In recent years, video tape recorders (hereinafter referred to as VTRs) have become widespread, and the major ones perform recording and reproduction using a carrier color signal low frequency conversion recording method. Block diagrams of the sub-〇 recording and reproducing system are shown in FIGS. 1 and 2.

The video signal input from input terminal 1 has a 1H delay □ line (H
A comb filter 2 whose constituent elements are a horizontal period), a luminance signal (hereinafter abbreviated as Y signal) and a color signal (hereinafter C
signals).

The Y signal is a low pass filter (hereinafter abbreviated as LPF) 3
After the band is limited by the Y-thread processing circuit 4, it undergoes processing such as FM modulation, passes through a bypass filter (hereinafter referred to as HPF) 5, is mixed with the C signal by a mixer 6, and is sent to all recording amplifiers 7. The entire image is recorded by the head 11. On the other hand, the C signal is separated by an A-shaped filter 2, and then filtered by a bandpass filter.
A post-digital processing circuit 9 whose band is limited by a filter (hereinafter abbreviated as BPF) 8 performs processing such as low frequency conversion.
o, f7c, and then mixed in keyaki combiner 6.

Here, the C signal may or may not pass through the comb filter 2.

Next, during playback, the playback signal played by the head 12 is amplified by the head amplifier 13 and then passed through the HPF 14 and LPF.
The Y signal and C signal are separated by l9. Y signal (d
After undergoing processing such as FM demodulation in the y-system processing circuit 15, the LPF
16i to the mixer 17, mixed with the C signal, and output to the terminal 18. On the other hand, the C signal is separated by the LPF 19, subjected to processing such as high frequency conversion by the C system processing circuit 2o, and then sent to the mixer 17 through the BPF 21'ii.

Here, in the C-system processing circuit, the comb filter 22 is often used to improve the S/N of the color signal.

Here, the comb filter 2 separates the Y signal and the C signal by taking the sum and difference with the signals before 1H, but this is possible because the C signal has a strong vertical correlation. There is.

However, in periods where the vertical correlation is weak or there is no vertical correlation, the separation of y and c is not performed well, that is, the 3.58 l component of the C signal leaks into the Y signal, or the C
The signal was causing uneven color, two colors, and a drop.

Now, for conventional home VTRs, the recording and playback band for Y signals was limited to 2 to 3 units.
F3. Due to the characteristics of LPFle, etc., it was limited to a band of 2 to 3 stones.

Therefore, the separation in the comb filter 2 is not complete, and the 3
．． Even if the color signal component of 58 rhinoceros leaks into the Y signal,
Since the reproduction band of the VTR is about 2 to 3, the leaked components do not interfere with recording and reproduction, and do not interfere with recording and reproduction.

On the other hand, by using a metal tape or the like as a recording medium, it is possible to obtain high-quality reproduced images. With this high quality VTR, the FM carrier frequency can be raised to about 1.5 degrees higher than before, making it possible to significantly expand the luminance signal band to about 4 degrees.

Here, if 3.58M color signal components that were not removed were mixed into the Y signal, these mixed components would be regarded as Y signal components and would be recorded and reproduced as they were, generating noise.

In other words, since the Y signal recording and reproducing band has been significantly extended, problems that could not occur in the past have arisen.

Purpose of the invention
? , .

The purpose of the present invention is to prevent color signals from being mixed into luminance signals.
・′, l.

An object of the present invention is to provide a magnetic recording and reproducing device that makes it possible to improve the deterioration of reproduced images caused by this.

, ' The magnetic recording and reproducing apparatus of the present invention checks the vertical phase of the color signal, and when the vertical correlation force 177 is weak, the recording or reproducing band of the luminance signal is limited.
', 1 It is possible to limit large color signals and obtain noise-free recorded and reproduced images.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In order to better understand the principle of the present invention, FIG. 3 shows waveforms of a conventional example. Figure 3a.

b, c, and d are a of the circuit blocks in FIGS. 1 and 2.

Waveforms b, c, and d are shown.

The input movie signal a has a waveform in which a C signal is superimposed on a Y signal. Although Y and C are separated by comb filter 2,
H intervals without vertical color correlation cannot be accurately separated. Therefore, the C signal is also included in the Y signal of b as the signal S1.

Due to the influence of the comb filter 2, the amplitude of the C signal decreases in sections where there is no vertical correlation, causing color distortion. In order to prevent this color blurring, the C signal may not be passed through the comb filter 2, and the input signal a may be directly sent to the BPF 8 for processing.

When these signals are recorded and reproduced, the noise S1, which is a 3.58WIh component in a VTR with a recording and reproduction band of 4, is reproduced as it is, and is output as a waveform shown in d for 7 pages. The shaded portion S3 in d is reproduced by overlapping Sl and S2, resulting in large noise. FIG. 4 shows a circuit block diagram according to an embodiment of the present invention. Further, FIG. 6 shows waveform diagrams of various parts corresponding to FIG. 4. This embodiment is different from the conventional device shown in FIG.
The difference is that a TRAP ) 27, a comparison circuit 26, and BPFs 24 and 25 are added. The comb filter 2 is only shown in some detail, and there is no difference from the conventional example. Here, DL23 is a 1H delay element.

The operation of each part will be explained using FIG. 6.

Here, a, b, c, d, e, f, g in Figure 6 are n
These correspond to those with the same reference numerals in FIG.

The input signal a is separated by a comb filter 2 into a Y signal and a C signal q. On the other hand, the 3.58 component of the input signal a and the signal delayed by t' by 1H has a BPF of 25. The signals pass through the BPF 24 and are sent to the comparison circuit 26 as signals c and d. The comparison circuit 26 compares the amplitude or phase of the signal C and the signal d, and generates a signal such as e according to the difference. Here, since various circuits for comparing amplitude or phase can be considered in the prior art, only a block diagram is shown in this embodiment. Now, the band limiting circuit 27 limits the band of the Y signal when the signal ef is a large input and at a high level. Here, the band limiting circuit 27 is L
It is composed of a PF or a band rejection filter (TRAP). That is, when the signal e is at a high level, the Y signal band is limited and the Y signal becomes like the Y signal f. In other words, it was possible to eliminate color signal leakage. The recording/reproduction output of these signals is shown in h. It can be seen that the noise seen in the conventional example is not generated at all.

Now, the present invention can be similarly applied to a reproduction system of a VTR. A block diagram of the reproduction system is shown in FIG.

Compared to the conventional example shown in FIG. 2, a comparator circuit 30 and a band limiting circuit 28 are added in the same manner as in the recording system. Although the content of the comb filter 22 is shown in some detail, it is not different from the conventional one. Here, DL29 is a 1H delay element.

Page 9 Now, let us assume that a recorded tape is to be played back using a conventional circuit. The waveforms at that time are shown in Figure 7 a, b, c, d, and e.

Shown in f. Here, it is assumed that the C signal does not pass through the comb filter 2 during recording.

The reproduced Y signal a reproduces the 3.58WPrl signal as it is. If the colors are mixed as is, the part 81 becomes noise.

According to the present invention, the reproduced negative signal and the color signal C delayed by 1H are input to a comparator circuit, and the amplitudes or phases are compared. As a result, the signal d is outputted in the same manner as that produced by the recording system.

When d is at a high level, TRAP2B performs band limitation, so Y signal a becomes signal e, which is mixed with the color signal and becomes signal f.
The following is output.

In other words, the present invention is effective whether it is implemented in either a recording system or a reproducing system, or may be implemented in both systems.

, Also, in the embodiment, output 1 of the comparison circuit 26.30
0 page Alternatively, it may be a digital signal that outputs a high level when the difference between the two human forces exceeds a predetermined value.

Similarly, the band control circuit 27.28 is connected to the comparison circuit 26.3.
Depending on the signal level from 0, the band limit amount may be changed analogously, or it may be a circuit that processes digitally.

Further, it is possible to insert only one of the comb-shaped filters inserted into the color recording/reproducing system, or they may not be inserted at the same time, but this is not directly related to the present invention.

In addition, in the embodiment, TRAP 27 and 28 provide luminance signals,
Although the recording/reproduction band of No. 5 is limited, various methods of this limitation can be considered. For example, even if the cutoff frequency of HPFa and HPF 14 through which the FM and modulated Y signals pass is shifted to a higher frequency range, the Y system band limit can be realized.
- Also, during normal recording, high frequency emphasis is performed in Y system 4, but the emphasis is
By stopping with the control signal e from 6, TRAP
The same function as 27 can be realized.

That is, by recording without applying emphasis during recording and applying de-emphasis during reproduction, it is possible to limit the high frequency range, and in other words, the TRAP circuit in the embodiment can be omitted.

Effects of the Invention As is clear from the above explanation, the magnetic recording and reproducing apparatus of the present invention detects the vertical correlation of color signals, and when the vertical correlation is weak, limits the recording and reproducing band of the luminance signal, thereby detecting the comb-shaped filter. It is possible to remove the color signal components that have leaked into the luminance signal without being removed in the previous step, and it is possible to obtain noise-free recording and playback images.This is particularly effective for high-quality VTRs with significantly extended recording and playback bands. There is something big about it.

[Brief explanation of the drawing]

Figures 1 and 2 are block diagrams of conventional recording/reproducing circuits.
Fig. 3 is a signal waveform diagram thereof, Fig. 4 is a block diagram of a recording system of a magnetic recording/reproducing apparatus according to an embodiment of the present invention, Fig. 6 is a signal waveform diagram thereof, and Fig. 6 is a reproduction of the same embodiment. The block diagram of the system and FIG. 7 are its signal waveform diagrams. 24.25...BPF, 26.30...
・Comparison circuit, 27.28...Band limit circuit, 2
, 22... Comb filter, 23.29...
...Delay element. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3

Claims (4)

[Claims] (1) A magnetic recording/reproducing device characterized by being provided with a detection means for detecting vertical correlation of color signals, and a limiting means for restricting a recording or reproduction band of a luminance signal when the vertical correlation is weaker than a predetermined amount. (2) The magnetic recording and reproducing apparatus according to claim 1, wherein the detection means detects a correlation in amplitude or phase between the color signal and a color signal before one horizontal period. (3) The magnetic recording and reproducing apparatus according to claim 1, wherein the limiting means limits the color signal component so that it is sufficiently attenuated. (4) The magnetic recording and reproducing apparatus according to claim 1, wherein the limiting means is performed by limiting the characteristics of a high-pass filter through which the FM-modulated luminance signal passes.