JPH0378394A - Magnetic recording/reproducing device - Google Patents

Abstract

PURPOSE:To prevent the deterioration of picture quality by shifting a color side band component on two-dimensional frequency, and inserting it into the signal of the same band as this, and synthesizing these signals by line-offsetting them in different phase directions. CONSTITUTION:The color side band component corresponding to the high band component of a base band chrominance signal is shifted on the two-dimensional frequency to the band of a horizontal band within 40fH+ or - 500kHz by a means 21 to obtain a signal CH and the means 28 to obtain the signal CH' by frequency-converting it, and is inserted into the signal CL of the same band. Besides, the signals CH and CH' are line-offset in the different phase shift directions, and are synthesized by an adder 29. In the case of the reproduction of this recorded signal, the signals CH' and CH are separated by a vertical direction filter 42, and a broad band chrominance signal can be obtained by demodulating and summing them. Thus, the bleeding of color or the deterioration of the picture quality can be prevented.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) This invention applies luminance/color separation (hereinafter referred to as Y/C) to an input video signal.
It relates to a magnetic recording and reproducing device that performs FM modulation on the luminance signal, converts the color signal to a low frequency, and combines these signals and records them on a magnetic tape. It is related to the system that is used.

(Prior art) In a magnetic recording/reproducing device, a color signal is converted to a low frequency (hereinafter referred to as a low-frequency converted color signal), a luminance signal is FM-modulated, and both signals are added and recorded on a magnetic tape. A one-sided color under recording method is used.

FIG. 8 is an explanatory diagram schematically showing a tape recording pattern formed by a VHS type magnetic recording/reproducing device and a color signal phase. The patterns of channels CHI and CH2 are obtained by two heads facing each other at 180 degrees around the circumference of the rotating drum, which represent several horizontal periodic sections.

The phase of the low-pass conversion color signal is distributed in a phase distribution of O"90'180"270' in the track of channel CHI, making one rotation in 4 horizontal synchronization intervals (hereinafter referred to as 4H), and in the track of channel CH2. is 0
'270'180@90'' is a phase distribution that rotates in the opposite direction.

FIG. 9 shows a system for performing color signal frequency conversion to obtain the tape pattern shown in FIG.

The human video signal is extracted by a bandpass filter 1,
The frequency converter 2 converts the signal to a lower frequency. The color signal converted to a low frequency is derived through a low pass filter 3. The frequency converter 2 is supplied with an idler signal that can provide the above-mentioned phase rotation.

The idler signal is f sc + 40fll (f sc
: color subcarrier frequency, fll: horizontal synchronization frequency). This idler signal is generated as follows. First, an fsc oscillation signal is output from the crystal oscillator 9 and supplied to the side frequency converter 10. - On the other hand, the horizontal synchronization signal of the input luminance signal is transmitted to the horizontal synchronization separation circuit 5.
is input to the 40 multiplier circuit 6,
11 frequency signals. This signal is input to the phase shifter 7 and distributed into signals of four types of phases. The output of the phase shifter is selected in a phase pattern corresponding to each channel by a switch 8 controlled by a channel switching pulse and a horizontal synchronizing pulse. The signal is supplied to the side frequency converter 10 and multiplied by the previous tsc oscillation signal. The output of the side frequency converter 10 is passed through the bypass filter 1
1 (or a bandpass filter) to the frequency converter 2 as a low-pass conversion color subcarrier frequency fs.

In the VHS system, phase shift (
P.S.) Processing is performed.

FIG. 10 shows the frequency spectrum of the low-pass converted color signal frequency-converted as described above.

The figure shows the low-pass conversion color subcarrier frequencies fs aligned.

FIG. 10 shows the spectrum in the β format and the 81-video format, and the spectrum in the VH3 format. FIG. 10(C) is the spectrum of the first channel CHI, and FIG. 10(D) is the spectrum of the second channel CH2.

The frequency at which the signal component in Figure (C) appears is 40ftl+(
There is 1/4)fH+nfH, and the frequency at which the signal component in FIG. (n-0, ±1.±2゜±3....) The idler signal in the β method and 8-line video has a phase change of 180' for each line in the first channel, and a phase change of 180' in the second channel. A method of conversion without phase switching is adopted. This is called phase inverting (PI) processing. (A) of the figure shows the spectrum of the first channel CHI, and (B) of the figure shows the spectrum of the second channel CH2.

The reason for controlling the carrier phase of the low-pass converted color signal as described above is to prevent crosstalk interference of color signals of adjacent tracks in both PI processing and PS processing, and guard panless without guard band between tracks. This is an effective method for recording and reproducing.

By the way, due to the balance with the luminance FM signal band, the low-frequency conversion color signal band is limited to a band of about fs±500K)lz. The same applies to the 5-VH8 method, in which the brightness signal band is widened to 5 MHz, and the rise time in the step response is 200 nsec to 250 ns.
In contrast, the color signal has been improved to 1.2 μsec, which is the same as before, resulting in noticeable color bleeding and deterioration of image quality.

(Three problems to be solved by the invention) As mentioned above, according to the conventional color signal low-frequency conversion method,
In consideration of the luminance FM signal band, the low-pass conversion color signal band is limited to only about ts±500 KHz, and the step response of the color signal is slow and color blur is noticeable, which is a factor in deteriorating image quality.

Therefore, it is an object of the present invention to provide a magnetic recording/reproducing device that can obtain a wide band of color signals.

[Structure of the Invention] (Means for Solving the Problems) The present invention converts a human-powered broadband color signal into a signal CL in the fsc±0.5MHz band (fsc: color subcarrier frequency) and fsc -0,5M)iz -f
means for band-separating the signal CH into a signal CH within the sc -1.5 MHz to fsc band;
means for converting the frequency into a Hz band to obtain a signal CH+";
The signals CL and CH! ' When converting ' to low frequency,
Means for converting the frequency to a low frequency using an idler signal obtained by inverting the phase of the l/4 line offset or l/2 line offset sequence, and adding these frequency converted signals and applying a low pass filter. Extract through F
It is provided with means for adding the M-modulated luminance signal.

(Function) By the above means, the tonal wave band components corresponding to the high frequency components of the baseband color signal are horizontally converted on a two-dimensional frequency by the means for obtaining the signal CH and the means for frequency converting this to obtain the signal CH'. The band within 401'H±500Ktlz of the band is shifted and inserted into the signal CL of the same band. Furthermore, the signals CH" and CL are line-offset and synthesized in different phase change directions. When reproducing this recorded signal, a vertical filter is used to generate the signal C11'.
By separating, demodulating, and adding CL and CL, a wideband color signal can be obtained.

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

FIG. 1 shows an embodiment of the present invention. The baseband video signal is Y/C separated, and the color signal is introduced into bandpass filters 20 and 21 via an input terminal IN. Bandpass filter 20 is 3,58±0.5M
The Hz band component (color signal low frequency component) is extracted and supplied to the frequency converter 22. pan dobas filter 21
is 3.58-0.5MHz ~ 3.58-1.5MHz
The band components (color signal high frequency components) are extracted and supplied to the frequency converter 24. As a result, the baseband color signal is separated into high-frequency components and low-frequency components.

The frequency converter 24 multiplies the signal from the conversion carrier oscillator 25 by the signal component in the I MHz band to obtain 3.58 MHz.
Convert to z-band signal. The conversion carrier oscillator 25 is
A carrier of 2.58 MHz is generated. The output signal from the frequency converter 24 is supplied to a bandpass filter 26 that extracts components in the 3.58±0.5 MHz band.

The output signal from this bandpass filter 26 is supplied to a frequency converter 28.

The frequency converter 22 is a circuit that converts the carrier color signal CL containing the low frequency component of the baseband color signal into a low frequency frequency, and the frequency converter 28 converts the carrier color signal 011 containing the high frequency component of the baseband color signal. This is a circuit that converts ′ to a low frequency.

The output signals of the frequency converters 22 and 28 are added together in an adder 29, and are derived through a low-pass filter 3o.

The signal is then combined with the luminance FM signal and recorded on the magnetic tape.

The frequency domain of the signals CL and CH' supplied to the adder 29 is shown in a two-dimensional frequency domain as shown in FIG. 7(A). FIG. 7(A) shows the first quadrant of the components of the first channel. The components of the second channel are represented by a distribution in which the positions of the signals CL and CH are swapped. Also, 1
When the spectrum is shown in terms of dimensional frequencies, it becomes as shown in FIG.

The signal CL has a spectrum as shown in FIG. 10(C), and the signal CH has a spectrum as shown in FIG. 10(D).

Here, the idler signals in the frequency converters 22 and 28 are obtained by idler signal generating means based on the principle explained in FIG. 9, respectively.

The frequency converter 22 is supplied with an idler signal from an idler signal generator 23, and the frequency converter 28 is supplied with an idler signal from an idler signal generator 27.

The phase of the idler signal from the idler signal generator 23 is changed for each IH in the first channel CHI as follows: 0990° 180@270° 0°..., and in the second channel CH2, the phase is changed as follows: 00270° 180° 90@ The direction of change is reversed, like 0@...

On the other hand, the idler signal from the idler signal generator 27 is IH in the first channel as 0@270@180'90'0'... in the second channel as 0@90"180@270" O@... The phase is changed every time. In other words, the idler signals from the idler signal generators 23 and 27 are controlled to rotate in phase in opposite directions.

FIG. 5 schematically shows a tape recording pattern obtained by performing the above processing. The arrow shown by a solid line represents the phase of the signal CL, and the arrow shown by a broken line represents the phase of the signal CH'.

Looking at the phase rotation directions of the signals CL and CF within the same channel, they are opposite to each other, and the first channel and the second channel
Even between channels, the phase rotation direction of each signal is opposite.

FIG. 2 shows a circuit for returning the low frequency converted color signal reproduced from the tape recorded as described above to the color signal of the original frequency.

The reproduced signal is introduced into a low-pass filter 41. The low frequency converted color signal extracted by this filter is input to a 90e offset comb filter 42. This comb-shaped filter 42 provides a path for adding the pre-IH signal to the original human power signal by 90'' phase rotation, and a path for subtracting it from the original human power signal.Thereby, a signal whose vector phases are opposite to each other ( CL or CF) and a signal in the same direction (
C11' or CL) can be created, so
Signals CHto and CL can be separated.

FIG. 3 shows a specific example of the 90@offset comb filter 42 described above.

The low frequency conversion color signal input to the input terminal 421 is 90'
It is supplied to a phase shifter 422, a subtracter 424, and an adder 425. The output of the 90″ phase shifter 422 is sent to the IH delay circuit 423.
After being delayed by , the signal is supplied to a subtracter 424 and an adder 425 . As a result, the subtracter 424 outputs the signal CL or C.
H' is obtained, and the adder 425 outputs the signal CH' or C
L is obtained. This signal is connected to selection circuits 428 and 42.
7 is input. The selection circuits 428 and 427 are switched field by field and deliver the signal CL to one output 429 and the signal C11 to the other output 430.

The explanation will be returned to FIG. 2. The previously separated signal CL is input to the frequency converter 44, and the signal CH' is input to the frequency converter 47. The frequency converter 44 is supplied with an idler signal from an idler signal generator 43 (corresponding to idler signal generator 23 in FIG. 1). The signal obtained from the frequency converter 44 is supplied to a band pass filter 45 with a band of 3.58±0.5 MHz. The signal output from this bandpass filter 45 corresponds to the low frequency component of the color signal. On the other hand, the frequency converter 47 is supplied with an idler signal from an idler signal generator 46 (corresponding to the idler signal generator 27 in FIG. 1).

The signal output from the frequency converter 47 passes through a processing path opposite to that during low-frequency conversion. That is, the frequency-converted signal is passed through a bandpass filter 4 in the 3.58±0.5MHz band.
8 to a frequency converter 50. The frequency converter 50 receives conversion carriers (2.
5MHz~fsc) is supplied. Therefore, the signal CH is restored from the frequency converter 50 and input to the bandpass filter 51. The band pass filter 51 includes 3.
Band components from 58-0.5 MHz to 3.58-1.5 MHz are extracted and supplied to adder 52.

As described above, a wideband color signal can be obtained from the adder 52.

In the above embodiment, the low frequency component and the high frequency component of the reproduced signal are separated at the low frequency stage. However, it is also possible to convert the reproduced signal into a carrier color signal of the original frequency and then separate it into low-frequency component and high-frequency component signals CL and CH+.

FIG. 4 shows yet another embodiment of the invention.

A reproduced signal is supplied to the input terminal 61 and introduced into the low-pass filter 62 . The low-pass converted color signal derived from the low-pass filter 62 is sent to a frequency converter 63 in 3.
It is converted to a 58MHz band signal.

The frequency converter 63 is supplied with an idler signal from an idler signal 64 . The rotational phase direction of the idler signal is controlled so that a signal C11 can be obtained from an adder 68, which will be described later. The output of the frequency converter 63 is 3
．． The signal is supplied to a band pass filter 65 that extracts the 58±0.5 MHz component.

The signal output from the bandpass filter 65 is supplied to an IH delay circuit 66, a subtracter 67, and an adder 68. A signal CL is obtained from the subtracter 67 and is supplied to the adder 72. On the other hand, a signal CH' is obtained from the adder 68,
This is input to frequency converter 69. Frequency converter 6
9 is supplied with a conversion carrier (for example, 100 KHz) from a conversion carrier generator 70. As a result, high-frequency components of the color signal are obtained and input to the bandpass filter 71. The bandpass filter 71 is 3.58-0.
The components of 5 MHz to 3.58 MIIz −1.5 MHz are extracted and supplied to the adder 72 . As a result, a broadband color signal is obtained from the adder 72.

A signal CL is obtained from the subtracter 67, and a signal CHo is obtained from the adder 68, which is generated by the idler signal generator 64 so that the color signals having the phases shown in FIG. 5 can be separated by a comb filter. This is because the phase of the idler signal is switched. For example, let's look at channel CHI.

Idler signal is 0” during H1 period and 90° during H2 period
When switching is made such as 180° in the H3 period and 270° in the H4 period, the signal before IH and the original signal can be subtracted to obtain the signal CL, and added to obtain the signal CH'.In channel CH2, conversely, 0 in H1 period @ 2 in H2 period
It is necessary to switch to 70 degrees, 180 degrees in the H3 period, and 90 degrees in the H4 period.

In this way, the system described above converts the frequency of the high frequency component of the color signal and embeds it in the low frequency side during recording, and when embedding it, the phase is controlled in a form that can be easily separated using a comb filter later, and then the embedding is performed and reproduced. The time is separated and the high-frequency and low-frequency components are combined again to obtain a wideband color signal.

The idea of this invention is not limited to the above-mentioned PS processing system, but can also be applied to a PI processing system.

FIG. 6 shows a tape recording pattern in the PI processing method. The solid arrow indicates the phase of the low frequency component of the color signal, and the broken line arrow indicates the phase of the high frequency component of the color signal. Figure 7(B) shows the signal in PI processing
It is expressed as a dimensional frequency, and when expressed as a one-dimensional frequency, the spectrum of the low frequency component CL is as shown in FIG. 10(A), and the spectrum of the high frequency component CH is as shown in FIG. 10(B).

To perform PI processing, the idler signal generator 23 of FIG.
．． 27 are set so that one always generates an idler signal with a fixed phase, and the other is controlled so that the phase is inverted by 180 degrees every IH.

Furthermore, the present invention can be easily adapted to recording and reproducing PAL signals by making slight modifications (modification of the idler signal phase switching algorithm).

In this embodiment, the phase rotation of color components, which was conventionally processed to prevent crosstalk between adjacent troubles, is utilized for multiplexing high frequency components. Therefore, it is preferable to provide a guard band between adjacent tracks.

Furthermore, when a tape recorded as described above is played back using a conventional playback system, the spatial frequency at which the signal CH is located is removed by a comb filter that removes adjacent crosstalk in PS processing, so the signal CL is It can be played without any problems.

[Effects of the Invention] As explained above, according to the present invention, it is possible to obtain a wide band of color signals, and it is possible to prevent color bleeding and image quality deterioration.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a recording system according to an embodiment of the invention, FIG. 2 is a block diagram showing a reproduction system according to an embodiment of the invention, and FIG. 3 is a diagram showing an example of a 90" offset comb filter. , FIG. 4 is a block diagram showing a reproduction system in an embodiment of this invention, FIGS. 5 and 6 are explanatory diagrams showing tape recording patterns formed by the apparatus of this invention, and FIG. 7 is a block diagram showing a reproduction system in an embodiment of this invention. FIG. 8 is an explanatory diagram showing a tape recording pattern of a device using conventional PS processing. FIG. 9 is a block diagram showing a conventional color signal conversion system. FIG. 10 is a diagram shown to explain an example of a spectrum of a color signal. 20.21.26.48.51.65.71... Bandpass filter, 22, 24, 28.44.47.50
．． 63.69...Frequency converter, 23.27.43.
64...Idler signal generator, 25.49.70...
・Conversion carrier generator, 29.52.68...Adder, 30.41.62...Low pass filter, 42...
-90'' offset comb filter, 66...IH delay circuit, 67...subtractor.

Claims (2)

[Claims] (1) In a magnetic recording/reproducing device that performs FM modulation on a luminance signal, converts the color signal to a low frequency, synthesizes it, and records the input wideband color signal in the fsc±0.5MHz band (fsc
: color subcarrier frequency), and (fsc-0
．． 5 MHz to fsc - 1.5 MHz) band and a second signal CH within the band; and means for frequency converting the second signal CH to an fsc ± 0.5 MHz band to generate a third signal CH'; When converting the first and third signals CL and CH' into low frequency frequencies, each idler signal of the sequence is rotated in phase by 90 degrees line by line so that the directions of rotation are opposite to each other, Magnetic recording characterized by comprising means for converting each frequency to a low frequency, and means for adding the frequency-converted signals, extracting them through a low-pass filter, and adding them to an FM-modulated luminance signal. playback device. (2) In a magnetic recording/reproducing device that performs FM modulation on a luminance signal, converts the color signal to a low frequency, synthesizes it, and records the input wideband color signal in the fsc±0.5MHz band (fsc
: color subcarrier frequency), and (fsc-0
．． 5 MHz to fsc - 1.5 MHz) band and a second signal CH within the band; and means for frequency converting the second signal CH to an fsc ± 0.5 MHz band to generate a third signal CH'; When converting the first and third signals CL and CH' to low frequency, each idler signal is converted to a low frequency using a sequence in which one is fixed phase and the other is switched by 180 degrees for each line. A magnetic recording/reproducing device comprising means for adding these frequency-converted signals, extracting them through a low-pass filter, and adding them to an FM-modulated luminance signal.