JPS63179695A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a video image with high picture quality by separating a luminance signal and a chrominance signal into two respectively, modulating and mixing them and recording them onto two recording tracks thereby improving the frequency utilizing effect. CONSTITUTION:The luminance signal Y is separated into signals Y1, Y2 by time expansion and frequency-modulated. The color signal C is separated into orthogonal components R-Y, B-Y and converted into a low frequency signal by amplitude modulation. Then the luminance signal after frequency modulation and color signal after amplitude modulation separated into two are mixed and recorded on the separate recording tracks. At the reproduction, the part corresponding to the synchronizing signal of the color signal or the amplitude in its vicinity are detected and the color signal is amplified so that the amplitude of the part comes to a prescribed value. Thus, the band width is doubled as to the luminance signal in comparison with a conventional band, the frequency utilizing efficiency is improved and the video image with high picture quality is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention (Industrial Application Field) The present invention relates to a magnetic recording/reproducing device (VTR), and more specifically, to a magnetic recording/reproducing device (VTR), in which a video signal is separated into two systems and separated into separate tracks on a magnetic tape. The present invention relates to a magnetic recording/reproducing device for recording data.

(Prior art) Methods for recording video signals on magnetic tape include (a) direct recording method, (b) color signal low frequency conversion method, and (C)
The time plex method and (d) two channel method are known.

The direct recording method frequency-modulates the video signal to be recorded and records it on a magnetic tape, and is mainly applied to broadcasting VTRs and the like that require high image quality.

The chrominance signal low-band conversion method separates the video signal to be recorded into a luminance signal and a chrominance signal, then frequency-modulates the luminance signal, and converts the chrominance signal into a frequency band lower than that frequency modulated wave. Both are mixed at the same ratio and recorded on magnetic tape, and are mainly applied to home VTRs.

The timeplex method separates the video signal into a luminance signal and a color signal, compresses the time axis of the color signal (and luminance signal if necessary), and then time-divides the two and arranges them on the same time axis.
This was frequency-modulated and recorded on magnetic tape, and was proposed as a European standard for 8mm VTRs.

In the two-channel recording method, the luminance signal is frequency-modulated and recorded on the first channel, and the color signal is encoded into two orthogonal components R-Y and B-Y, time-division multiplexed, and then frequency-modulated. It records on the second channel,
It is mainly applied to commercial VTRs.

Incidentally, in order to reduce the magnetic tape consumption Z and to effectively utilize the necessary frequency band determined by the tape/head system, it is a prerequisite to adopt a card bandless recording method using azimuth recording.

On the other hand, in the short wavelength range, it is possible to eliminate crosstalk from adjacent tracks due to azimuth loss, but this is not possible in the long wavelength range. It is necessary to remove crosstalk from

Considering the above conditions, the direct recording method, time-plex method, and two-channel method must transmit video information using only one frequency-modulated wave, resulting in poor utilization efficiency in the long wavelength range. On the other hand, the color signal low-pass conversion method is satisfactory in terms of frequency utilization efficiency, but when the recording video signal frequency band is expanded to the limit frequency of 4.2 MH2 determined by the NTSC system for high-quality VTRs, the carrier of the frequency modulated wave is If it cannot be set high, there is a problem in that moiré occurs in the demodulated signal, degrading the image quality. In addition, since the color signal processing is the same as the method used in current home VTRs, the noise added by the tape/head system causes phase fluctuations and amplitude fluctuations, resulting in hue fluctuations and purity fluctuations. There is a problem in that the quality of the reproduced image deteriorates.

(Problems to be Solved by the Invention) As described above, conventional magnetic recording and reproducing devices have problems such as poor frequency utilization effects or poor image quality. The present invention has been made in view of these points, and its purpose is to provide a magnetic recording and reproducing device that has good frequency utilization efficiency and high image quality.

[Structure of the Invention] (Means for Solving the Problems) The present invention includes a first separation circuit that separates an input video signal into a luminance signal and a color signal, and a first separation circuit that divides the luminance signal into a first luminance signal by time expansion. a time expansion circuit that separates the color signal into a first color signal and a second color signal, a second separation circuit that separates the color signal into a first color signal and a second color signal, and a time expansion circuit that separates the color signal into a first color signal and a second color signal; first and second frequency modulation circuits that perform frequency modulation; and amplitude modulation of the first and second color signals.
and first and second amplitude modulation circuits that convert the output signal of the second frequency modulation circuit into a signal on the lower frequency side; a first mixing circuit that mixes the output signal and records it on a first recording track of the magnetic tape; and mixes the output signal of the second frequency modulation circuit and the output signal of the second amplitude modulation circuit. The second mixing circuit records on the second recording track of the magnetic tape and detects the amplitude of a portion of the reproduced amplitude modulated color signal corresponding to the synchronization signal or its vicinity, and determines that this portion has a predetermined amplitude value. The above object is achieved by providing a gain control circuit that amplifies the amplitude modulated color signal so that the amplitude modulated color signal becomes .

(effect) The video signal is separated into a luminance signal and a color signal.

Among these, the luminance signal is separated into two signals by time expansion and frequency modulated. On the other hand, the color signal consists of two orthogonal components (
After the signal is separated into R-Y and B-Y (or I, Q) signals, it is converted into a low frequency signal by amplitude modulation.

The two separated frequency-modulated luminance signals and amplitude-modulated color signals are mixed and recorded on separate recording tracks.

During reproduction, the amplitude of a portion of the color signal, which is an amplitude modulated wave, corresponding to the synchronization signal or its vicinity is detected, and the color signal is amplified so that the amplitude of this portion becomes a predetermined value. That is, since the color signal in the conventional color signal low-pass conversion method includes a color burst signal, the amplification gain can be controlled based on the amplitude of the color burst signal, and the amplitude of the reproduced color signal can be controlled to be constant. However, since the color signal in the present invention is recorded as an amplitude modulated wave, there is no color burst signal.

Therefore, we focused on the fact that the sync signal part where no color information exists or the part near it has a constant amplitude even after being amplitude modulated by the color signal, and during playback, the amplification gain is controlled based on the amplitude of this part. .

Therefore, since the luminance signal is separated into two by time expansion, the band is twice as large as that of the conventional method, and frequency utilization efficiency is improved. Furthermore, since two orthogonal components of the color signal are recorded on separate tracks, hue component noise is reduced and fluctuations in the time axis direction are also suppressed. Further, adjacent crosstalk can be easily removed by phase shifting, phase inverting, or the like. As a result, it is possible to obtain high-quality video with good frequency utilization efficiency.

(Example) Hereinafter, the present invention will be described in detail based on Examples.

FIG. 1 is a block diagram of a recording system showing one embodiment of the present invention, and FIG. 2 is a block diagram of a reproduction system. Further, FIG. 3 is a diagram showing the frequency spectrum of the signal recorded in the embodiment for each track. First, the frequency spectrum shown in FIG. 3 will be explained. In Figure 3, Yl and Y
2 is a signal obtained by reducing the luminance signal frequency band of the recorded video signal by half, and subjected to frequency modulation by a predetermined carrier deviation, and fH or 1/2f) ((fH is By causing an offset in the horizontal synchronizing signal frequency (horizontal synchronizing signal frequency), components of crosstalk from adjacent tracks that cannot be removed by azimuth loss are removed.

On the other hand, CI and C2 represent color signals separated into R-Y and B-Y components, and the input color signal C is R-Y
After being converted into a signal and a B-Y signal by a color decoding circuit, each signal is amplitude-modulated so as to have a frequency interleaved relationship, mixed with the luminance signal Y1 or Y2 at an appropriate ratio, and recorded on a magnetic tape. Ru.

When trying to record other information other than video signals, such as audio signals, at the same time, the frequency is modulated in the frequency range between Yl and RY or Y2 and B-Y at a rate of 1 carrier per transmission path. simultaneously R-Y, Yl or B-Y
, Y2 at an appropriate ratio for recording.

Next, the recording system will be explained.

In FIG. 1, a video signal to be recorded is separated into a luminance signal Y and a color signal C by a Y/C separation circuit (not shown). The Y signal is roughly separated into two signals Yl and Y2 by expanding the time axis by two times, for example, in units of horizontal synchronizing signals, by a doubling expansion circuit 1.

Note that if the video signal is such that the frequency band of the Y signal is 4.2 MH2, each frequency band of Y11 times and Y22 times is 2.1 MH2.

Yl and Y22 times are input to the luminance signal processing circuit 2゜3, and after being subjected to processing such as predetermined emphasis,
The signal is sent to frequency modulation circuits 4 and 5, subjected to frequency modulation using a predetermined deviation carrier offset, and sent to the next addition circuits 6 and 7.

On the other hand, the telegram @C is converted into two orthogonal components by the color decoding circuit 8 and output.

For example, if you use the R-Y axis and the B-Y axis as the conversion axes,
A R-Y signal and a B-Y signal are output from the color decoding circuit 8.

The RY signal and the B-Y signal are sent to color amplitude modulation circuits 9 and 10, respectively. The color amplitude modulation circuits 9 and 10 include an amplitude modulation circuit 11, a balanced modulation circuit 12, and a local oscillation circuit 13.
It is made up of etc. In the amplitude modulation circuit 11, a color subcarrier (so-called 3,58 MH2
) to perform amplitude modulation using the R-Y signal and B-Y signal. The frequency oscillated by the local oscillation circuit 13 has a frequency difference of 1/2fh between the color amplitude modulation circuits 9 and 10,
The difference between the frequency and the color subcarrier is set to be a predetermined low-frequency conversion carrier. The carrier from the local oscillation circuit 10 and the modulated wave from the amplitude modulation circuit 11 are respectively sent to a balanced modulation circuit (not shown), and the color signals CI and C2 converted to low frequencies are sent to an addition circuit (6, 7> sent to.

Adding circuits 6 and 7 add the frequency modulated wave of the Y1 signal and the C1 signal, and the frequency modulated wave of the Y2 signal and the C2 signal at an excessive ratio. In this case, if necessary, a third signal (for example, audio signal @) may be added between the frequency modulated wave and the C1 or C2 signal, and a fourth signal may be added to the lower frequency range than the C1 or C2 signal. may be applied to either one or both at the same time.

The output signals of the adder circuits 6 and 7 are sent to a recording circuit (not shown), and the frequency spectrum of each of these output signals is as shown in FIG.

Next, the reproduction system shown in FIG. 2 will be explained. Note that only color processing is illustrated here, and since the same circuit is required for each channel, only one channel is illustrated.

From the reproduced signal sent from the reproduction circuit, only the color low-frequency conversion signal is extracted by the filter 20, and then the AG
The signal is sent to the C circuit 21. Here, a synchronization signal of the reproduced color signal or a position signal corresponding to the vicinity including the synchronization signal is sent to the AGC circuit 21 from a reproduced luminance signal processing system (not shown).

Therefore, the AGC circuit 21 controls the gain so that the amplitude of the reproduced color signal specified by the position signal becomes a predetermined level. As a result, the reproduced color signal from which level fluctuations have been removed is sent to the balanced modulation circuit 22, where it is balanced modulated by the carrier in the local oscillation circuit 23 and output as a reproduced color signal amplitude-modulated with a predetermined carrier. .

The output signal of the balanced modulation circuit 22 is transmitted to the comb filter circuit 24.
The crosstalk between adjacent tracks is removed, and then the detection circuit 25 converts the R-y signal (or B-
y signal) and then sent to the encoder circuit 26.
The same telegram as recorded @ C1: is restored and output.

By controlling the amplitude of the color signal in this manner, it is possible to eliminate level changes in the reproduced color signal that occur in the tape head system.

Further, the balanced modulation circuit/local oscillation circuit in the recording system and the balanced modulation circuit/local oscillation circuit in the reproduction system can be the same. In general, most of the circuits of the current color low-frequency conversion system can be used.

As explained above, according to this embodiment, the luminance signal is time-stretched and separated into two, the color signal is also separated into two orthogonal components, and these separated words are modulated and then mixed. Since recording is performed on two recording tracks, the band of the luminance signal is expanded to 4.2 MH in the case of a TSC signal.
It has become possible to easily transmit up to 2, and the C/N
Since it becomes possible to use a low F~1 carrier frequency with a good value, the S77\ of the video is improved. Furthermore, the color signal is an amplitude modulated signal, and during playback, the gain is adjusted based on the amplitude near the synchronization signal, so the hue can be reproduced without being affected by the P~1 component of the noise components. This improves hue reproducibility. In addition, as for the circuit configuration, most of the conventional circuits can be used as is, so development costs are low, and high image quality and high sound quality video can be recorded in a format similar to the recording format of the conventional home V-R. The effect is that it can be achieved with

;Effects of the Invention] As described above, according to the present invention, it is possible to provide a magnetic recording reproducing device that has good frequency utilization effects and can obtain high-quality images.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram of a recording system showing an embodiment of the present invention, FIG. 2 is a block configuration diagram showing an embodiment of a reproduction system,
FIG. 3 is a spectrum diagram showing recording signal frequency spectra of two recording tracks in the example. 1...2x expansion circuit 2.3...Luminance signal processing circuit 4.5...Frequency modulation circuit 6.7...Adder 8...Decoding circuit 9.10...Color amplitude modulation Circuit 21...AGC circuit agent Patent attorney Noriyuki Chika Yudo Hiroshi Uji Figure 1 Figure 3

Claims (1)

[Claims] a first separation circuit that separates an input video signal into a luminance signal and a chrominance signal; a time expansion circuit that separates the luminance signal into a first luminance signal and a second luminance signal by time expansion; a second separation circuit that separates a signal into a first color signal and a second color signal; first and second frequency modulation circuits that frequency modulate the first and second luminance signals; and first and second amplitude modulation circuits that amplitude modulate the second color signal and convert it into a signal on the lower frequency side than the output signals of the first and second frequency modulation circuits, and the first frequency modulation circuit. a first mixing circuit that mixes the output signal of the circuit and the output signal of the first amplitude modulation circuit and records it on the first recording track of the magnetic tape; the output signal of the second frequency modulation circuit; mixing with the output signal of the second amplitude modulation circuit,
A second mixing circuit records on a second recording track of the magnetic tape and detects the amplitude of a portion of the reproduced amplitude modulated color signal corresponding to the synchronization signal or its vicinity, and this portion becomes a predetermined amplitude value. A magnetic recording/reproducing device comprising a gain control circuit for amplifying an amplitude modulated color signal.