JPH04344793A - Magnetic recorder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording device which is applied to, for example, a video tape recorder (hereinafter referred to as VTR) and is adapted to magnetically record frequency multiplexed signals.

0002

[Prior Art] FIG. 5 shows, for example, "Introduction to Home VTR" (
Conventional VT published on page 150 of Corona Publishing)
1 is a block diagram showing the configuration of a signal processing circuit of R. In the same figure, 1 is a Y/C separator that separates an input video signal into a luminance signal Y and a color signal C. 2 is a luminance signal processing circuit, which is composed of an emphasis, an FM modulator, and the like. Reference numeral 33 denotes a color signal processing circuit, which is composed of a frequency converter and the like. 4 is an adder, 5 is a recording amplifier, 6
is a magnetic head, and 7 is a magnetic tape.

[0003] Next, the operation of the above configuration will be explained. The video signal input to the Y/C separator 1 is separated into a luminance signal Y and a color signal C. Among them, the luminance signal Y undergoes emphasis and FM modulation in the luminance signal processing circuit 2 to become an FM luminance signal. On the other hand, the color signal C is frequency-converted to a low frequency range in the color signal processing circuit 33, and becomes a low frequency converted color signal.

F output from the luminance signal processing circuit 2
The M luminance signal and the low frequency converted color signal output from the color signal processing circuit 33 are added together in an adder 4, and then sent to a recording amplifier 5.
The current is transmitted to the magnetic head 6 as a current, and the magnetic head 6 magnetically records on the magnetic tape 7. Here, Fig. 6(a)
indicates the spectrum of the recording signal, and in the same figure, 28
31 is a carrier for the low frequency conversion color signal, and 31 is a carrier for the FM luminance signal.

FIG. 7 is a block diagram showing a specific configuration of the above color signal processing circuit 33, which is similar to the above-mentioned "home VT".
It is also published on page 165 of ``Introduction to R'' (published by Corona Publishing). In the figure, 8 is a bandpass filter (hereinafter referred to as BPF), 9 is an automatic color signal level adjuster (hereinafter referred to as ACC), 16 is a frequency converter, 15 is a local oscillator, and 17 is a frequency converter.
is a low-pass filter (hereinafter referred to as LPF).

The operation of the color signal processing circuit 33 having the above configuration will be explained. The color signal separated and output by the Y/C separator 1 described above passes through the BPF 8 and is input to the ACC 9, where level fluctuations are suppressed to a small level. Next, the output of the local oscillator 15 is multiplied by the frequency converter 16 to generate the sum and difference frequencies of the local oscillation frequency, and the LPF 1
7 to select the low frequency side, low frequency conversion is performed.

[0007]

Since the conventional magnetic recording device is constructed as described above, when a signal recorded by this device is reproduced, a spectrum as shown in FIG. 6(b) is obtained. In the figure, 29 and 30 are distortion components in magnetic recording, and it is known that the FM luminance signal carrier 31 is amplitude-modulated at twice the frequency of the low frequency conversion color signal carrier 28. These distortion components 29 and 30 appear as beats in the reproduced video signal and deteriorate the image quality. For these reasons, the recording level of the low-frequency conversion color signal cannot be raised above a certain limit, and therefore the color signal reproduction S/
There was a problem that N could not be made sufficient.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a magnetic recording device that can improve image quality by reducing distortion components generated during reproduction. shall be.

[0009]

[Means for Solving the Problems] A magnetic recording device according to the present invention amplitude-modulates an FM luminance signal of a frequency multiplexed signal at a frequency twice that of a color signal, and also modulates the amplitude of the FM luminance signal of a frequency multiplexed signal at a frequency twice that of the color signal. It is characterized by having the same spectrum arrangement as that of the signal.

[0010] Furthermore, as a frequency converter for the color signal,
There are two systems.

[0011]

[Operation] According to the present invention, by amplitude modulating the FM luminance signal at twice the frequency of the low frequency conversion color signal and recording it, it is possible to reduce the distortion components that occur during playback. The color signal recording level can be set high.

[0012] Furthermore, by providing two systems of frequency converters in the color signal recording processing system, it is possible to match the spectrum arrangement of distortion components generated during playback with the modulation spectrum arrangement during recording. Distortion that occurs can be sufficiently suppressed.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a magnetic recording device according to an embodiment of the present invention.
, 2, 4-9, 15-17 and 33 are shown in FIGS. 5 and 7
Since this is the same as the conventional example shown in FIG.

In FIG. 1, reference numeral 3 denotes an amplitude modulator that amplitude-modulates the FM luminance signal output from the luminance signal processing circuit 2 at twice the frequency of the color signal. 10 is a local oscillator, and 11 is a frequency converter, which are provided corresponding to the local oscillator 10. 12 is a BPF, 13 is a phase shifter, and 14 is an attenuator.

Next, the operation of the above configuration will be explained. The processing of the luminance signal system is the same as in the conventional example, so the explanation will be omitted. In the processing of the color signal system, first, the color signal C separated by the Y/C separator 1 passes through the BPF 8, is amplitude modulated by the ACC 9, and is then input to two frequency converters 11 and 16, respectively. These frequency converters 11 and 1
6 is the same configuration, for example a multiplier, and the local oscillator 10
and 15 into mutually different frequencies.

Here, the frequency of one local oscillator 15 is Fs+Fls, where Fs is the color subcarrier frequency and Fls is the low frequency conversion frequency, and the frequency converter 16 lowers the carrier of the color signal from Fs to Fls. Area conversion. Moreover, the frequency of the other local oscillator 10 is Fs+2・Fl
The frequency converter 11 converts the color signal carrier from Fs to Fls, which is twice as high as Fs. The output of the one frequency converter 16 is as in the conventional example,
The output of the other frequency converter 11 passes through the BPF 12 and is guided to the adder 4 through the LPF 17.
3 and an attenuator 14 and are suitably phase-shifted and attenuated,
The signal is input to the amplitude modulator 3.

In the above amplitude modulator 3, the FM luminance signal, which is the output of the luminance signal processing circuit 2, is amplitude-modulated at twice the frequency of the color signal to produce amplitude modulation distortion as shown in FIG. 6(b). 29 and 30, the amplitude is modulated in advance during recording. In this way, amplitude modulated FM
A luminance signal is outputted from the amplitude modulator 3, added to the low frequency converted color signal by an adder 4, amplified by a recording amplifier 5, and recorded on a magnetic tape 7 via a magnetic head 6.

According to the above configuration, the arrangement of the souktram is corrected as follows. First, the operation of the frequency converter 16 will be explained with reference to FIG. In the same figure, 26
is a modulated color signal, and the upper sideband side is indicated by diagonal lines. 27
is the frequency of the local oscillator 15, and 28 is the low frequency conversion color signal. Frequency 27 of local oscillator 15 (Fs+Fls
) and the frequency (Fs) of the modulated color signal 26 is converted to the frequency from DC (0 Hz), so the lower side band wave side shown by diagonal lines of the low-pass converted color signal 28 is the upper side band of the modulated color signal 26. It corresponds to the wave side.

The spectrum shown in FIG. 3(a) is as shown in FIG.
This is the spectrum shown in b) with added sideband waves. As shown in the figure, it is clear that the sideband waves of the amplitude modulation distortions 29 and 30 due to the low frequency conversion color signal 28 are arranged in correspondence with each other by the shaded areas. In the case of amplitude modulation during recording, the spectrum arrangement must be the same as that of the amplitude modulation distortions 29 and 30, so the spectrum must be as shown in FIG. 3(b). In other words, the shaded area shown in FIG. 3(b) must correspond to the shaded area of the modulated color signal 26 and the low frequency conversion color signal 28.

It is obvious that the above can be realized by the above embodiment. For example, if the frequency is doubled after low-frequency conversion, the spectrum arrangement may be reversed, and in that case, the distortion suppression effect will be halved.

FIG. 4 is a block diagram showing the configuration of a magnetic recording apparatus according to another embodiment of the present invention. In this embodiment, multipliers are used for the two frequency converters 11 and 16.
Instead, a method of demodulating color signals is adopted.

In FIG. 4, 18 is a burst separation circuit;
19 is a carrier regeneration circuit, 20 is a color signal demodulator, 21,
25 is a color signal modulator, 23 and 24 are frequency dividers, and 22 is a phase shifter. Since the other configurations are the same or equivalent to those of the embodiment shown in FIG. 1, the same reference numerals are given to the corresponding parts and the explanation thereof will be omitted.

Next, the operation of the configuration shown in FIG. 4 will be explained. The operation up to ACC9 is the same as in the above embodiment, and therefore the explanation will be omitted. The output of the ACC 9 is input to a burst separation circuit 18 to separate the burst signal, and then a color subcarrier is recovered by a carrier recovery circuit 19. This color subcarrier causes the color signal to become a color difference signal in the demodulator 20, and by modulating this color difference signal with two types of carrier waves, the same operation as in the above embodiment is achieved. First, the frequency divider 23 converts the color subcarrier into a frequency of 2.Fls. This is suitably phase-shifted by a phase shifter 22 and a modulator 21
is input. This modulator 21 generates a color signal of a carrier wave of 2.Fls.

On the other hand, the output of the frequency divider 23 is input to the frequency divider 24, and its frequency becomes Fls, which is then input to the modulator 2.
5 to obtain a low frequency converted color signal. At this time,
Since both the modulators 21 and 25 are adjusted so that the spectrum arrangement is correct, the sideband arrangement is as shown in 28 and 32 in FIGS. 2 and 3. And the modulator 21
The output passes through the BPF 12 and is appropriately attenuated by the attenuator 14 before being input to the amplitude modulator 3. The subsequent operations are similar to those in the above embodiment, and therefore will not be described. The above embodiment also provides the same effects as the above embodiment.

Although each of the above embodiments is shown as an analog signal processing circuit, the same effect can be obtained by using a digital processing circuit with a similar configuration using an analog-to-digital converter or a digital-to-analog converter. play.

Further, in the above embodiment, a magnetic recording device using a magnetic tape has been described, but it is also possible to apply the present invention to other magnetic recording devices such as a magnetic disk device.

Further, in the above embodiment, only the relevant parts in the color signal processing circuit have been described in detail, but other conventional circuit configurations such as a burst amplification circuit, a phase shift conversion circuit, and an emphasis circuit are originally included. This is what is happening.

[0028]

[Effects of the Invention] As described above, according to this invention, FM
By recording the luminance signal by amplitude modulating it at twice the frequency of the low-frequency conversion color signal, it is possible to suppress the amplitude modulation distortion component that occurs during playback, and thereby the recording level of the color signal during recording can be suppressed. Can be set high. Therefore, the reproduction S/N of the color signal can be made sufficient, and the quality of the reproduced video signal can be significantly improved.

In particular, by providing two systems of frequency converters in the color signal recording processing system, it is possible to match the spectral arrangement of distortion components occurring during reproduction with the modulation spectral arrangement during recording. Distortion that occurs can be sufficiently suppressed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a magnetic recording device according to an embodiment of the present invention.

FIG. 2 is a spectrum diagram illustrating the operation of a frequency converter.

FIG. 3 is a diagram illustrating a spectrum of amplitude modulation distortion.

FIG. 4 is a block diagram showing the configuration of a magnetic recording device according to another embodiment of the invention.

FIG. 5 is a block diagram showing the configuration of a conventional magnetic recording device.

FIG. 6 is a diagram showing frequencies of amplitude modulation distortion in the case of FIG. 5;

FIG. 7 is a block diagram showing the configuration of a conventional color signal processing circuit.

[Explanation of symbols]

1 Y/C separator 2 Luminance signal processing circuit 3 Amplitude modulator 4 Adder 9 ACC 10,15 Local oscillator 11, 16 Frequency converter 13 Phase shifter 14 Attenuator 33 Color signal processing circuit

Claims (2)

[Claims] 1. A magnetic recording device configured to convert a chrominance signal into a low frequency range and frequency-modulate a luminance signal for magnetic recording, the FM luminance signal being converted into a chrominance signal in the 2nd frequency range.
1. A magnetic recording device comprising: an amplitude modulator that performs amplitude modulation at twice the frequency; and the spectral arrangement of the color signal and the signal having twice the frequency thereof are configured to be equal. 2. As a frequency converter for the color signal, 2
2. The magnetic recording device according to claim 1, further comprising a system.