JPH0378393A - Magnetic recording/reproducing device - Google Patents

Abstract

PURPOSE:To prevent the bleeding of color or the deterioration of picture quality by separating a chrominance signal into a low frequency band chrominance signal and a high frequency band chrominance signal, and PS-processing and low-band-converting the high frequency band chrominance signal by an idler signal, and summing and recording both the signals. CONSTITUTION:In a recording system, the chrominance signal is separated into the low frequency band chrominance signal and the high frequency band chrominance signal according to a frequency band by a color band separation circuit 22, and the low frequency band chrominance signal is processed by PS(phase shift) processing and low band conversion similar to an example in the past, and the high frequency band chrominance signal is processed by the PS processing and the low band conversion by the idler (carrier) signal given a field offset by a 90 deg. phase shifter 31. Accordingly, even if both the signals are summed up by an adder 24 and recorded, they never interfere each other. Thus, since the frequency band of the chrominance signal can be expanded, the bleeding of the 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 synthesizes 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. 5 is an explanatory diagram schematically showing a tape recording pattern formed by a VH3 type magnetic recording/reproducing apparatus and color signal phases. 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 0° 90'180"270@ in the track of channel CHI, and the phase distribution is such that it rotates once in 4 horizontal opening periods (hereinafter referred to as 4H), and in the track of channel CH2. 0' in
This is a phase distribution that rotates in the opposite direction to 270"180@90°.

FIG. 6 shows a system for performing color signal frequency conversion to obtain the tape pattern shown in FIG.

The input 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 fsc+40fH (fse: color subcarrier frequency, fH: horizontal synchronization frequency). This idler signal is generated as follows. First, fs
An oscillation signal of c 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 separated in the horizontal synchronization separation circuit 5 and inputted to the 40 multiplier circuit 6 to become a frequency signal of 4OfH. This signal is input to the phase shifter 7 and 48
It is distributed into signals of phase i. The output of the phase shifter 7 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 fsc oscillation signal. The output of the side frequency converter 10 is supplied to the frequency converter 2 as a low-pass conversion color subcarrier frequency fs via a bypass filter 11 (or a bandpass filter). In the VHS system, phase shift (PS) processing is performed as described above.

FIG. 7 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. 6 shows the vector spectrum in the β format and the 8-video format, and the spectrum in the VH8 format. FIG. 6(C) is the spectrum of the first channel CHI, and FIG. 6(D) is the spectrum of the second channel CH2.

The frequency at which the signal component in (C) appears is 40r11+(
The frequency at which the signal component in Figure (D) appears is 40fH-(3/4)fil±n.
It is tH. (n-0, ±1.±2±3....) The idler signal in the β system and 8■■ video has a phase change of 180' for each line in the first channel, and A method of converting without 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.

As mentioned above, the carrier phase of the low frequency conversion color signal is tila
The reason for this is that both PI processing and Ps processing are used to prevent crosstalk interference of color signals of adjacent tracks, and are effective methods for performing guard panless recording and reproduction without guard bands between tracks.

By the way, due to the balance with the luminance FM signal band, the low-frequency conversion color signal band is limited to only about fs±500KIIz. The same applies to the 5-VHS system, in which the brightness signal band is widened to 5 MHz, and the rise time in step response is 200 nscc to 25 MHz.
In contrast, the color signal has been improved to 0 nsec, but the color signal still has a rise time of about 1.2 μsec, which makes color bleeding noticeable and causes image quality deterioration.

(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 fs±500 KHz, and the step response of the color signal is slow, resulting in noticeable color blurring, which is a factor in deteriorating image quality. Low conversion color signal band is fs±50
The reason why it is 0 KIIz is because the carrier frequency of the low-pass conversion color signal is the standard of 629K I (z) and cannot be made higher.

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 provides a magnetic recording/reproducing device for recording or reproducing color signals, in which (f V , f t ) is used as a recording system circuit at least in the vertical-temporal frequency domain. = (N/4(CY,/
p, h ), N/2(Ilz) ) and (-N/4
(CY, /p,h) , -N/2(llz)) (
However, the carrier color signal existing in the area where the carrier frequency is N: the number of scanning lines in one frame, M: frame frequency) is divided into a low-range color signal that is a horizontal low-range color component and a high-range color component in the horizontal direction. (f V , f t ) −(N/l1l(CY,
#1. h), N/4 (Hz)) and (-N/8
(CY, /p, h) , -N/4 (Hz)) as a carrier, a first frequency shifter that frequency-shifts the low-pass color signal to a region where (f V , f t ) = (N/8); (CY, /
p, h ), -N/4(Hz)) and (-N/8(
CY, /p, h), N/4(lIz)) for frequency shifting the low frequency color signal to a region having carriers; and a second frequency shifter that is the output of the first and second frequency shifters. an adder for adding the first and second low-band converted color signals to obtain a wide-band low-band converted color signal; a separation circuit that separates the first low-frequency conversion color signal into a signal and a second low-frequency conversion color signal;
, h ), N/2(Hz) ) and (-N/4(C
Y, /p, h), -N/2 (Hz)) as a carrier frequency; N/4(CY, /p
, h ), N/2(Hz) ) and (-N/4(C
A fourth frequency shifter that returns the carrier frequency to the region where the carrier frequency is and an adder for obtaining a carrier color signal.

(Function) With the above means, in the recording system, the color signal is separated into a low-range color signal and a high-range color signal, and the low-range color signal is subjected to PS processing and low-range conversion as in the past. is,
The high frequency color signal is subjected to PS processing and low frequency conversion using an idler (carrier) signal applied with a field offset. Thereby, even if both signals are added and recorded, they will not interfere with each other. In addition, in the reproduction system, the low-range converted color signal is separated into color bands, and the low-range converted color signal is reproduced into the original high-range color signal in the same way as before. As for the color signal, processing is performed to reproduce the original high-frequency color signal by passing it through the processing path opposite to that during recording. Therefore, by adding the reproduced low-range color signal and high-range color signal, a wideband color signal can be recorded and reproduced. This means that a larger amount of information (high frequency components) can be recorded and reproduced without changing the carrier frequency for recording the low frequency converted signal.

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

FIG. 1 shows a recording system in one embodiment of the present invention. The baseband video signal is Y/C separated, and the color signal is introduced into a band-limiting filter 21 via an input terminal 20 . Band limit filter 21 is 3.58MHz
All components other than the broadband color signal component having a band of ±1.5 MHz with the center at 1 are removed. The wideband color signal obtained from the band-limiting filter 21 is supplied to a band-pass filter 221 and a subtracter 222 that constitute the band-separation filter 22.

A 3.58±0.5 MHz color signal component (low-range color signal) is extracted from the bandpass filter 221. Therefore, when the output of the bandpass filter 221 (low-band color signal) is subtracted from the output of the band-limiting circuit 21 (wide-band color signal component) in the subtracter 222, the high-band color signal component can be obtained from the subtracter 222. can.

The low frequency color signal is input to the multiplier 23, multiplied by the idler signal, and subjected to PS processing. The idler signal is output from the idler signal generator 26, and the phase is rotated by 90'' every horizontal period to obtain the recording pattern as explained in FIG. 4.The frequency of the idler signal is 3.5
8MHz+4Of'll (fit: horizontal frequency)
It is. As a result, a low frequency converted low frequency color signal can be obtained from the multiplier 23. This low-pass converted low-pass color signal is
After being inputted to the adder 24 and combined with the low-pass converted high-pass color signal, it is derived as a recording signal via the low-pass filter 25.

On the other hand, the high frequency color signal is input to the frequency shifter 27.

This frequency shifter 27 includes multipliers 271.273.90
"It is composed of a phase shifter 272, 2701 and a subtracter 274, and shifts the frequency of the high-range color signal by (3,58/4) MHz. This frequency-shifted high-range color signal is
By passing the signal through a bandpass filter 28 having a center frequency of 8 MHz, only the lower band of the high-frequency color signal (the upper band is removed) is extracted. Next, this frequency-shifted high frequency color signal is input to a multiplier 29, where it is converted to a low frequency signal. This conversion process is also a PS process, but the idler signal used for this process is phase controlled as follows.

That is, the phase of the idler signal is rotated so as to obtain a recording pattern as shown in FIG. In FIG. 3, the arrows shown by solid lines in each horizontal period are the phases of the low-band converted low-band color signals, and the arrows shown by broken lines are the phases of the low-band converted high-band color signals. The part that controls the phase of this idler signal is a 90″ phase shifter 3.
1 and switch 30.

The low frequency converted high frequency color signal obtained from the multiplier 29 is supplied to the pilot information adding circuit 32. Here, the phase switching information of the idler signal for the high frequency color signal is superimposed as pilot information at a position other than the picture period of the low frequency converted color signal. The low-pass converted high-pass color signal to which the pilot information has been added is input to the adder 24 via the switch 33, and is combined with the low-pass converted low-pass color signal.

The switch 33 is used to decide whether or not to combine the low-frequency converted high-frequency color signal with the low-frequency converted low-frequency color signal.
It is turned on and off by a control signal from 4. The reason for providing the switch 33 is as follows. In the reproduction system, as will be described later, the low-frequency converted high-frequency color signal and the low-frequency converted low-frequency color signal are separated, returned to their original frequencies, and recombined to reproduce a wideband color signal. In this case, filtering (interfield calculation) is performed between fields to separate signals. If there is a moving image between fields, this will be separated as a low-frequency conversion high-frequency color signal, resulting in color disturbance. I'm trying to get only that.

As a result, a low-pass converted broadband color signal is obtained from the adder 24, harmonic components are removed by the low-pass filter 25, and the signal is derived as a color signal for recording.

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

Figure 2 shows the reproduction system.

The reproduced low-pass color signal is supplied to the input terminal 41 and taken out via the low-pass filter 42. This signal includes a low-frequency converted high-frequency color signal and a low-frequency converted low-frequency color signal, and is input to the color signal separation circuit 43 . The separation circuit 43 is
It includes a delay circuit 431 for one field, a delay circuit 433 for 2H, and subtracters 432 and 434. Since the subtracter 432 performs arithmetic processing between fields, the third
As can be seen from the phase vector in the figure, by subtracting the low-pass converted color signal of the adjacent line (subtractor 432), a low-pass converted high-pass color signal can be obtained. Further, by performing subtraction processing (subtractor 434) between signals at positions shifted by 2H between adjacent tracks, a low-frequency converted low-frequency color signal can be obtained.

The separated low-pass converted low-pass color signal is input to a multiplier 44 and multiplied by an idler signal from an idler signal generator 45. This idler signal is output in accordance with the phase of the low frequency converted color signal shown in FIG. 3 (PS processing) to generate a low frequency color signal of the original frequency. The low frequency color signal obtained from the multiplier 44 has its harmonic components removed by a bandpass filter 46, is extracted as a signal in a band of 3.58±0.5 MHz, and is input to an adder 47. Adder 47
Then, a high-frequency color signal, which will be described later, is added. The wideband color signal obtained from the adder 47 is then input to a vertical filter 48, where crosstalk from adjacent tracks is removed and output.

The low-pass converted high-pass color signal is input to a multiplier 51 and multiplied by the idler signal. The idler signal is supplied in accordance with the phase of the low-frequency converted high-frequency color signal shown in FIG. The switch 61 performs phase switching processing. The signal obtained from the multiplier 51 passes through a bandpass filter 52 and is output as a high-frequency color signal component.

This high-frequency color signal component is frequency-shifted during recording. Therefore, in order to return to the original frequency position, it is input again to the multiplier 53 and the MH
It is multiplied by the carrier of z. The signal is then input to a bandpass filter 54 that extracts high-frequency color signals. The bandpass filter 54 is a bandpass filter having a center frequency of 3.7 MHz, and extracts a necessary lower sideband wave. As a result, a high frequency color signal is reproduced from the bandpass filter 54 and inputted to the adder 47 via the switch 55.

As explained in the recording system, the switch 55 is turned off by a control signal from the motion detection circuit 56 so that the output of the bandpass filter 54 is not added to the low-frequency color signal in a moving picture area.

The output of the bandpass filter 52 is also supplied to a pilot information detection circuit 57. Pilot information detection circuit 57
The method uses pilot information superimposed on the high-frequency color signal component to determine whether the switching algorithm of the switch 61 matches the algorithm at the time of recording.
If they do not match, the mode of the switch 61 is controlled to change the mode so that they match.

The above embodiment focuses on the fact that when color signals are viewed in the vertical-temporal frequency domain, low-pass converted color signals subjected to conventional PS processing exist only in the first and third quadrants. A low-frequency conversion low-frequency color signal with a low-frequency component is placed in the first and third quadrants, and a low-frequency conversion high-frequency color signal with a high-frequency component of the color is placed in the second and fourth quadrants. Then, they are added or separated.

That is, in the recording system, the color band separation circuit 22 shown in FIG.
t ) −(N/4(CY,/p,h), N/
2(llz) ) and (-N/4(CY, /p,h)
, -N/2 (Hz)) (where N: number of scanning lines in one frame, M: frame frequency) as carrier frequency It is separated into a color signal and a high-range color signal, which is a high-range color component in the horizontal direction.

FIG. 4(A) shows the frequency domain of the color signal, and the shaded area is the high frequency color signal domain. Next, the multiplier 23 part functions as a first frequency shifter, and (f V , f t ) = (N/8(CY, /
p, h ), N/4(Hz) ) and (-N/8(
CY, /p, h), -N/4 (Hz)) is used as a carrier to shift the frequency of the low frequency color signal. Also, the multiplier 29 functions as a second frequency thick, and (f V , f t ) = (N/8(CY, /
p, h ), -M/4(Hz)) and (-N/8(
The high frequency color signal is frequency-shifted to a region in which carriers are CY, /p, h), Mha(llz)). Figure 4 (
B) is the frequency domain of the low-pass converted high-pass color signal.

On the other hand, in the reproduction system, the multiplier 44 functions as a third frequency shifter and converts the low-pass converted low-pass color signal into (f V ,
f t ) = (N/4(CY, /p, h ),
N/2 (Hz) ) and (-N/4 (CY, /p, h
), -N/2 (Hz)) as the carrier frequency.

In addition, the multipliers 51 and 53 function as a fourth frequency shifter, and convert the low-frequency converted high-frequency color signal into (f V , f t ) −(N/4(CY, /p
, h ), N/2(Hz) ) and (-N/4(C
Y, /p, h), -N/2 (Hz)) is returned to the region where the carrier frequency is.

[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 tape recording formed by the apparatus according to the invention. FIG. 4 is an explanatory diagram showing a frequency domain for explaining the present invention in detail. FIG. 5 is an explanatory diagram showing a tape recording pattern of an apparatus using conventional PS processing. FIG. 7, a block diagram showing a conventional color signal conversion system, is a diagram shown to explain an example of a color signal spectrum. 21... Band limit circuit, 22.43... Color band separation circuit, 23.29.44.51.53... Multiplier, 2
4...Adder, 25.42...Low pass filter,
26.45...Idler signal generator, 27...Frequency shifter, 28.46.52.54...Band pass filter, 30.33.55.61...Switch, 31
．． 60...90@phase shifter, 32...pilot information addition circuit, 34.56...motion detection circuit, 57...
Pilot information detector. Figure 3 (A) (B) Figure 3

Claims (1)

[Claims] In a magnetic recording and reproducing device that records or reproduces a color signal, the recording system circuit includes, at least in the vertical-temporal frequency domain, (fV, ft) = (N/4 (CY./ph), M/2
(Hz)) and (-N/4(CY./ph), -M/
2 (Hz)) (where N: number of scanning lines in one frame, M:
Color band separation that separates a carrier color signal existing in a region where the carrier frequency is (frame frequency) into a low-range color signal that is a low-range color component in the horizontal direction and a high-range color signal that is a high-range color component in the horizontal direction. circuit, (fV, ft) = (N/8(CY./ph), M/4
(Hz)) and (-N/8(CY./ph), -M/
4 (Hz)) as a carrier;
4 (Hz)) and (-N/8 (CY./ph), M/
4 (Hz)) as a carrier; and first and second low-frequency converted color signals that are outputs of the first and second frequency shifters. and an adder for adding the reproduced wide-band converted color signals to the first low-frequency converted color signal and the second low-frequency converted color signal, and the reproduction circuit includes at least the reproduced wide-band converted color signals to the first low-frequency converted color signal and the second low-frequency converted color signal. a separation circuit that separates the first low-frequency conversion color signal into (fV, ft)=(N/4(CY./ph), M/2
(Hz)) and (-N/4(CY./ph), -M/
2 (Hz)) as a carrier frequency; /2
(Hz)) and (-N/4(CY./ph), -M/
2 (Hz)) as a carrier frequency, and an adder that adds the outputs of the third and fourth frequency shifters to obtain a reproduced wideband carrier color signal. A magnetic recording/reproducing device characterized by: