JPH01264398A - Magnetic recording/reproducing device - Google Patents

Abstract

PURPOSE:To suppress the decrease of resolution and to enhance an SN ratio by outputting the chrominance signal of a restored base band through a noise decreasing means and outputting a luminance signal from 8 restoring means and the chrominance signal with approximately corresponding to each other. CONSTITUTION:A reproducing system time base processing circuit 17 executes a time base processing contrary to that at the time of recording, and restores a Y signal to be the luminance signal and a Comega signal and a CN signal to be both chrominance signals. The noises of the restored Comega signal and the restored CN signal are respectively decreased, and the signals are inputted through noise decreasing circuits 18 and 19 respectively having a constant delay time tau1 for frequencies to a reverse matrix circuit 20. In a reproducing system time base processing circuit 17, the restored Y signal delays the reading of the Y signal to the Comega signal and the CN signal, for example, when the Y signal, Comega signal and CN signal written into a memory are read. Thus, the restored Y signal is outputted by being delayed for the constant time t, with respect to the Comega signal and the CN signal, and inputted to the reverse matrix circuit 20 conforming to the delay time tau1 of the noise decreasing circuits 18 and 19.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention performs time axis compression and expansion processing on luminance signals and chrominance signals, respectively, and records and reproduces them by time division multiplexing, thereby reducing noise in the luminance signals and chrominance signals. The present invention relates to a magnetic recording/reproducing device.

[Conventional technology]

In conventional magnetic recording and reproducing devices, a circuit for reducing noise is inserted into the reproduced luminance signal in order to reduce the influence of noise on reproduced images.

For example, a circuit that reduces noise by adding a low-frequency signal that passes a luminance signal through a low-pass filter and a high-frequency signal that passes through a bypass filter and removes noise using a base clip circuit using two diodes, or There are circuits that reduce noise by extracting and subtracting from a one-dimensional luminance signal.

As this type of noise reduction circuit, for example, [Home VTR
"Introduction", co-authored by Katsuya Yokoyama et al. (Corona Publishing, October 1981), p. 162-163.

[Problem to be solved by the invention]

In the above-mentioned conventional technology, noise is reduced for a luminance signal recorded in baseband, but no particular consideration is given to noise reduction for a chrominance signal recorded in the form of a carrier signal.

Furthermore, there is a problem in that the high-frequency components of the luminance signal are lost by the noise reduction circuit, resulting in unnatural image quality.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic recording and reproducing apparatus that effectively reduces noise on color signals and reduces the influence on reproduced images due to the insertion of this noise reduction circuit.

[Means to solve the problem]

The above object is a video signal recording and reproducing device which records a baseband luminance signal and a color signal, compresses the baseband color signal in the time axis, and records the baseband color signal by time-axis multiplexing it. Among the signals obtained by reproducing the signal, a noise reduction circuit is applied to at least the baseband chrominance signal to reduce the noise, or the baseband luminance signal and chrominance signal obtained by reproducing the signal are This is achieved by making the noise reduction degree of the noise reduction circuit for the chrominance signal larger than the noise suppression degree of the noise reduction circuit for the luminance signal when the noise reduction circuit acts on both of the chrominance signal and the luminance signal.

[For production]

A device that compresses the time axis of a color signal and reproduces a signal recorded by time-axis multiplexing the luminance signal requires a means to expand and restore the time axis of the color signal in the reproduced signal. Accordingly, the noise and interference signals included in the reproduced color signal are converted to a lower frequency, so that they become more noticeable, which can be effectively reduced by the noise reduction circuit provided for the reproduced color signal. In addition, the noise reduction circuit does not act on the reproduced luminance signal, or even if it does, the degree of noise suppression is small, so it is possible to reduce the decrease in resolution, and the overall balance is good.S/N is improved and high image quality is achieved. Obtainable.

〔Example〕

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

FIG. 1 is a block diagram showing an embodiment in which the present invention is applied to a time-axis multiplex recording type magnetic recording/reproducing device, in which three primary color signals red (R), green (G), and blue (B) are used. The video signals input from the R input terminal 1, G input terminal 2, and B input terminal 3, which are the respective input terminals of
It is converted into signal C of signal 6 and signal 7, and is input to the recording system time axis processing circuit 8.

The recording system time axis processing circuit 8 is composed of an A/D, a memory, a D/8, etc., and outputs a recording signal 9 obtained by subjecting the input Y signal 5, Cω signal 6, and CN signal 7 to time axis processing.

FIG. 2 is a waveform diagram for explaining the above time axis processing, in which (a) is the input Y signal 50 waveform, (b) is the input Cω signal 6 waveform, and (C) is the input Y signal 50 waveform. (d) shows the waveform of the recording signal 9. FIG.

The Y signal has a band several times larger than that of the Cω signal and the CN signal. In this example, the luminance signal (Y signal)
The time axis of is expanded (or compressed) by n□ times for each horizontal scanning line.6 Also, the Cω signal and C, signal are expanded (n2 times (n, > 1) and n1 times (nail), respectively, on the time axis).
The signal is compressed into the Y signal and time-division multiplexed onto the expanded Y signal. As a result, a recording signal 9 is generated. Here, nL
.

nz+na is a number set so that the frequency band of the Y signal, the frequency band of the Cω signal, and the frequency band of the C signal in the recording signal are approximately equal.

In this way, the recording signal 9 outputted from the recording system time axis processing circuit 8 in FIG. Ru.

During reproduction, the signal reproduced by the magnetic head 14 is amplified by a reproduction amplifier 15, frequency demodulated by a frequency demodulation circuit 16, and input to a reproduction system time axis processing circuit 17.

The reproduction system time axis processing circuit 17 includes an A/D and a memory.

It is composed of a D/A, etc., and performs time axis processing opposite to that during recording to restore the Y signal, Cω signal, and CN signal. That is,
From the signal reproduced from the recorded signal shown in FIG. 2(d), n
The Y signal component, which has been expanded (or compressed) on the time axis by a factor of □, is separated and compressed (or expanded) on the time axis by a factor of n1 to restore the Y signal shown in FIG. 4(a). Furthermore, the Cω signal component, which has been time-axis compressed by n2 times, is separated from the reproduced signal and expanded by n2 times, thereby restoring the Cω signal shown in FIG. 4(b).

Furthermore, the CN signal component, which has been time-axis compressed by n1 times, is separated from the reproduced signal, and the time-axis is expanded by n3 times, thereby restoring the C signal shown in FIG. 3(c).

The above-mentioned restored Cω signal and restored CN signal each have a constant delay time τ□ with respect to the frequency, and the noise is reduced through the noise reduction circuits 18 and 19 whose noise suppression degrees are NR process and NR2, respectively, and are converted into an inverse matrix. It is input to the circuit 2o.

On the other hand, the restored Y signal is a Y signal written in, for example, a memory in the reproduction system time axis processing circuit 17.

When reading the Cω signal and the CN signal, by delaying the reading of the Y signal with respect to the Cω signal and the CN signal, the output is delayed by a fixed time τ1 with respect to the Cω signal and the CN signal, and the noise reduction circuit 18. 19 delay time τ□
It is input to the inverse matrix circuit 20 in accordance with the time.

FIG. 3 is a block diagram showing an embodiment of the noise reduction circuit 18, 19 to which the restored Cω signal and the restored CN signal are input, and FIG. 4 is a waveform diagram illustrating its operation.

In FIG. 3, a reduced component of the signal input from the input terminal 24 (FIG. 4(a)) is extracted by a low-pass filter 25 having a constant delay time τ regardless of the frequency (the fourth
Figure (b)) is input to the L adder 31.

On the other hand, the input signal also has a constant delay time τ regardless of the frequency, and a high-frequency component is extracted by a bypass filter 26 having an amplitude characteristic opposite to that of the low-pass filter 25 (FIG. 4(c)). The signal is input to a base clip circuit 29 composed of 27 and 28. The above-mentioned high-frequency components are removed by a base clipping circuit 29, in which signals below a certain amplitude tn (shown in FIG. 4(c)) according to the degree of noise suppression are removed (FIG. 4(d)), and amplified by an amplifier 3o ( (Fig. 4(e)), the adder 31 adds the low-frequency component input from the low-pass filter 25 (Fig. 4(e)).
f)) is output to the output terminal 32.

Therefore, by operating the noise low-pass circuits 18 and 19 on the Cω signal and the C signal restored in the reproduction system time axis processing circuit 17 of FIG.
It is possible to effectively remove the noise in the flat part of the signal, the restored signal C, and the double signal, thereby improving the image quality.

Next, the restored Y signal input to the inverse matrix circuit 20,
The restored Cω signal and the restored CN signal are R signals.

The C signal and the B signal are converted to the R signal output terminal 21. The signal is output to the C signal output terminal 22 and the B signal output terminal 23.

Furthermore, in human visual characteristics, the sensitivity to the Cω signal and the CN signal is lower than the sensitivity to the Y signal, so the resolution of the reproduced image is almost determined by the frequency characteristics of the restored Y signal. Therefore, by operating the noise reduction circuits 18 and 19 only on the restored Cω signal and the restored CN signal, respectively, there is an effect that the influence of the noise reduction circuits 18 and 19 on the resolution of the reproduced image is reduced.

Further, a noise reduction means having a constant delay time of 2 is also arranged between the reproduction system time axis processing circuit 17 and the inverse matrix circuit 20, and acts on the Y signal output from the reproduction system time axis processing circuit 17. In this case, the noise suppression degree (N R ) of the noise reduction means is reduced by the noise suppression in each of the noise reduction circuits 18 and 19 that act on the Cω signal and the CN signal output from the reproduction system time axis processing circuit 17. degree N
Set NR,<NR1 to NR2 for R and NR2, and apply the restored Y signal from the reproduction system time axis processing circuit 17 to the restored Cω signal and the restored CN signal for a certain period of time (
The object of the present invention can also be achieved by outputting the signal with a delay of .tau.1- (in order to set the delay time of the restored Y signal to .tau.1).

FIG. 5 is a block diagram showing another embodiment of the present invention,
This is an example in which the present invention is applied to a magnetic recording/reproducing device that processes two color difference signals line-sequentially.

In FIG. 5, R input terminal 1. The video signals input from the G input terminal 2 and the B input terminal 3 are outputted to the matrix circuit 4 as Y signals 5. It is converted into a Cω signal 6 and a CN signal 7. The Y signal 5 output from the matrix circuit 4 is input to the recording system time axis processing circuit 35, and the Cω signal 6. C and signal 7 are input to the line sequential circuit 33. The line sequential circuit 33 switches and outputs the Cω signal and the CN signal for each line, thereby generating a line sequential color signal (C signal) 34 and inputting it to the recording system time axis processing circuit 35. In the recording system time axis processing circuit 35, the Y output from the matrix circuit 4
Signal 5 (Figure 6(a)) expands its time axis by n□ times (
or compressed).

Also, the C signal 34 (sixth
In Figure (b)), the time axis is compressed by n2 times, and the recording signal 36 (Figure 6 (C)) is time-division multiplexed with the expanded Y signal.
becomes. The recording signal 36 output from the recording system time axis processing circuit 35 is frequency modulated by the frequency modulation circuit 10, amplified by the recording amplifier 11, and then output from the magnetic head 12 to the magnetic tape 1.
Recorded in 3.

During reproduction, the signal reproduced by the magnetic head 14 is amplified by the reproduction amplifier 15, frequency demodulated by the frequency demodulation circuit 16, and subjected to time axis processing opposite to that during recording by the reproduction system time axis processing circuit 37, and is converted into Y signal and It is restored to C signal. That is, in the reproduction system time axis processing circuit 37, the Y signal component, which is time axis expanded (or compressed) by n1 times, is separated from the reproduced signal (FIG. 6(C)) output from the frequency demodulation circuit 16.
The time axis is compressed (or expanded) by n0 times and becomes the restored Y signal (FIG. 6(a)). Also, from the above reproduced signal, n2
The C signal component compressed in time axis is separated and expanded in time axis by n2 times to become a restored C signal (FIG. 6(b)).

The restored C signal outputted from the reproduction system time axis processing circuit 37 has a constant delay time, and the noise is reduced in the noise reduction circuit 38 whose noise suppression degree is NR9, and the noise is reduced by line sequential processing in the interpolation circuit 39. The missing components are interpolated to restore the Cω signal and the CN signal, which are input to the inverse matrix circuit 20.

On the other hand, the Y
The signal is output with a fixed time delay of 3 with respect to the C signal, and is input to the inverse matrix circuit 20. The inverse matrix circuit 20 receives the input Y signal.

The Cω signal and the CN signal are converted into an R signal, a C signal, and a B signal, and the R signal output terminal 21. G signal output terminal 2
2 and B signal output terminal 23.

It is clear that the same effect as the embodiment shown in FIG. 1 can be obtained in this case as well. Further, in this case, there is an advantage that only one system of noise reduction circuit for color signals is required. Further, a noise reduction means having a constant delay time τ4 is also arranged between the reproduction system time axis processing circuit 37 and the inverse matrix circuit 20, and acts on the Y signal output from the reproduction system time axis processing circuit 37. In this case, the noise suppression degree (NR4) of the noise reduction means is set as the noise suppression degree (NR4) of the noise reduction circuit 38.
5), NR, <NR.

The object of the present invention can also be achieved by setting , and outputting the restored Y signal from the reproduction system time axis processing circuit 37 with a delay of a certain time (τ3-τ4) with respect to the restored C signal.

In the above embodiments, a circuit having the configuration shown in FIG. 3 was used as a noise reduction means, but the present invention is not limited to this. For example, it is possible to utilize screen correlation using a frame memory, an adder, etc. It is clear that other noise reduction means, such as reducing noise by the following, may be used, and in that case, the same effect as that of this embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, a noise reduction circuit can be provided for the reproduced color signal, so that the noise components included in the reproduced color signal can be effectively reduced. In addition, the noise reduction circuit does not act on the reproduced luminance signal, or even if it does, the degree of noise suppression is small, so the reduction in resolution can be reduced. A magnetic recording and reproducing device can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a waveform diagram explaining the operation of time axis processing in FIG. 1, and FIG. 3 is a block diagram showing an embodiment of the noise reduction circuit. Fourth
5 is a waveform diagram illustrating the operation of the noise reduction circuit, FIG. 5 is a block diagram illustrating another embodiment of the present invention, and FIG. 6 is a waveform diagram illustrating the operation of the time axis processing in FIG. 5. 4... Matrix circuit, 8.35... Recording system time processing circuit, 17.37... Playback system appropriate time axis processing circuit. 18.19.38... Noise reduction circuit, 20... Inverse matrix circuit, 33... Line sequential circuit, 39... Interpolation circuit.

Claims (1)

[Claims] 1. In a magnetic recording and reproducing device that modulates and records and reproduces the luminance signal and color signal of a video signal while maintaining the baseband,
a restoring means for restoring a baseband luminance signal and a color signal from the reproduced signal; and an output means for outputting the baseband color signal from the restoring means via the noise reduction means; 1. A magnetic recording and reproducing apparatus characterized in that the luminance signal is output from the output means in substantially the same timing as the color signal from the output means. 2. In a magnetic recording and reproducing device that modulates and reproduces the luminance signal and color signal of the video signal as it is at the baseband,
a restoring means for restoring a baseband luminance signal and a chrominance signal from the reproduced signal; a means for outputting the baseband luminance signal from the restoring means via a first noise reduction circuit; The baseband color signal is
output means for outputting the output via the noise reduction circuit, wherein the degree of noise suppression of the first noise reduction circuit is lower than the degree of noise suppression of the second noise reduction circuit, and the first noise reduction circuit A magnetic recording/reproducing device characterized in that it is configured to output a luminance signal from the second noise reduction circuit and a color signal from the second noise reduction circuit in substantially the same timing. 3. In a magnetic recording/reproducing device that records and reproduces two simultaneous baseband color signals line-sequentially and time-division multiplexed with the baseband luminance signal, the baseband luminance is determined from the reproduced signal. separation means for separating the line-sequential color signal from the baseband signal; output means for outputting the color signal from the separation means via a noise reduction circuit; and a line-sequential color signal from the output means. It has a restoring means for restoring the original two simultaneous color signals, and is configured to output the luminance signal from the separation means with timing substantially matching the two simultaneous color signals from the restoring means. A magnetic recording/reproducing device characterized by: 4. Output means for outputting the luminance signal from the separation means via a second noise suppression degree having a noise suppression degree smaller than the noise suppression degree of the noise reduction circuit, 4. The magnetic recording and reproducing apparatus according to claim 3, wherein the luminance signal is outputted at substantially the same timing as the two simultaneous color signals from the restoring means.