JPH0585117B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a color video signal magnetic recording device and a magnetic reproducing device, and in particular, the present invention relates to a color video signal magnetic recording device and a magnetic reproducing device. The present invention relates to a color video signal magnetic recording device and a magnetic recording and reproducing device that convert the pseudo component signal into a component signal and record it on a magnetic recording medium, and also duplicate the reproduced pseudo component signal from the magnetic recording medium into the original composite color video signal.

2. Description of the Related Art In general, when handling composite color video signals with a VTR, it is necessary to carefully consider three points: the influence of time axis fluctuations, frequency bands, and waveform distortion (spurious). Here, the "direct color process method" used in broadcast VTRs addresses these considerations without compromise, but on the other hand,
For example, color video signals are recorded and played back by direct frequency modulation (FM) at a high relative speed between the tape and the head, on the order of 25 to 40 m/s, which requires highly accurate mechanics, large-scale circuits, and the use of a large amount of tape. The disadvantage is that a large amount is required.

On the other hand, in the "color under method" used in consumer or industrial VTRs, the relative speed of the tape head is relatively low, for example, on the order of several m/s, and the color signal is transferred to the FM band of the luminance signal. Since the frequency is converted to a lower frequency of around 700 kHz and the FM luminance signal is superimposed for recording and playback, the drawbacks of the above-mentioned broadcasting VTR have been improved.

Problems to be Solved by the Invention However, when a composite color video signal is recorded and reproduced in a conventional color video signal magnetic recording device and magnetic recording/reproducing device such as the above-mentioned “color under method” in the VTR, the composite color video signal is The problem was that only about 1/2 of the amount of information held was actually reproduced, resulting in insufficient resolution, sharpness, and color resolution, as well as a lack of detail in the reproduced image of the VTR.

Therefore, the present invention aims to convert a composite color video signal into a plurality of systems of pseudo component signals and record them on a magnetic recording medium, and to restore the reproduced pseudo component signal from the magnetic recording medium to the original composite color video signal. Therefore, it is an object of the present invention to provide a color video signal magnetic recording device and a magnetic recording/reproducing device that solve the above-mentioned problems.

Means for Solving the Problems The color video signal magnetic recording device according to the present invention has the following features:
Composite color video signal at sampling frequency n・
fsc (where n is an integer of 2 or more, fsc is the color subcarrier frequency of the composite color video signal), and an A/D converter that converts and outputs the sampling data obtained by analog-to-digital conversion; Within the scanning period, the sampling data of each period 1/fsc is converted into a group of n types of sampling data in total, and the n types of sampling data groups are combined in series in groups, m (however, m is an integer satisfying 2≦m≦n) means for dividing into parallel output systems, m systems of D/A converters for separately converting the m systems of sampling data groups from digital to analog, and m systems of D/A converters. A
Each output analog video signal of the converter is FM modulated and m tracks are separately recorded on a magnetic recording medium, and
It is composed of m systems of recording means that simultaneously form and record.

On the other hand, the color video signal magnetic recording and reproducing device according to the present invention includes means for configuring the color video signal magnetic recording device, as well as a means for recording previously recorded signals on a magnetic recording medium.
m systems of playback means for outputting playback signals obtained by playing back tracks of a book separately and simultaneously;
After demodulating the system playback signal, the sampling frequency
nfsc′ (however, fsc′ is the color subcarrier frequency of the reproduced signal)
m systems of A/D converters that sample in parallel and output a total of m systems of reproduced sampling data, and each output sampling data of the m systems of A/D converters is stored respectively, resulting in a total of n types of reproduced sampling data. A digital signal group, a means for sequentially extracting each reproduced sampling data one by one from each group in the original order and outputting the reproduced sampling data in series, and converting the extracted reproduced sampling data from digital to analog to the original and means for restoring the composite color video signal.

Function After the composite color video signal is sequentially converted into sampling data, the data arrangement is converted, etc., and converted into the n types of sampling data groups, which are serially combined in group units, and are divided into m systems. It will be done. This m-system sampling data group is converted into m-system analog video signals by m-system D/A converters, and then FM-modulated by m-system recording means and recorded on a magnetic recording medium.
In this case, m systems of analog video signals are stored separately on m tracks on the magnetic recording medium, and
recorded at the same time.

Thereafter, m systems of reproduction signals (m systems of reproduced analog video signals) reproduced by m systems of reproduction means are converted into m systems of reproduction sampling data by m systems of A/D converters, and then Signal processing is performed in the opposite manner to that during recording, and the original composite color video signal is eventually restored.

Next, an embodiment of the apparatus of the present invention will be described with reference to FIGS. 1 to 3.

Embodiment FIGS. 1 and 2 are block diagrams of an embodiment of a recording system and a reproducing system of a color video signal magnetic recording apparatus and a magnetic recording/reproducing apparatus according to the present invention, respectively.

This embodiment uses four rotating heads as described later.
The present invention is characterized in that the composite color video signal is divided into two systems of pseudo component signals using H ₁ to _{H 4} and recorded simultaneously on two tracks.

First, the operation of the recording system of the apparatus of the present invention will be explained with reference to FIG. 1 and FIGS. 3A to 3E.

In FIG. 1, a composite color video signal as shown in FIG.
and the timing pulse generation circuit 4, respectively. By the way, as is well known, the above composite color video signal has a color subcarrier frequency fsc (for example, fsc = 3.58MHz in the case of the NTSC system, fsc = 3.58MHz in the case of the PAL system)
This is a signal obtained by band-sharing multiplexing a carrier color signal obtained by quadrature modulating a 4.43MHz) color subcarrier with two types of color difference signals and band-sharing multiplexing it with a luminance signal.

The timing pulse generation circuit 4 separates a horizontal synchronization signal from the incoming composite color video signal, and generates a timing pulse P with a period of one horizontal scanning period (1H) obtained by waveform shaping the horizontal synchronization signal. The signals are supplied to a phase locked loop (PLL) 5 and a control device 6, respectively. Based on the incoming timing pulse P, the PLL 5 has a frequency of 4fsc, for example.
(In the case of the NTSC system, a pulse signal P ₁ of 4 fsc≈14.32 MHz) and a 4-phase pulse signal P ₂ of a frequency fsc whose phases are shifted by 90 degrees from each other are generated and supplied to the control device 6, respectively.

The control device 6 generates a sampling pulse Ps with a frequency of ₄ fsc, a write control signal Pw, a read control signal P _R , and a pulse signal P ₃ based on the pulse signal P 1, respectively, and controls the A/D converter 3 and the random access signal. - It supplies the memory (RAM) 7 and the D/A converter 8, respectively, and also generates an address signal _PA based on the pulse signals _P1 and _P2 and supplies it to the PAM7.

The A/D converter 3 samples the incoming composite color video signal with the sampling pulse Ps having a sampling frequency of 4fsc to generate digital data with, for example, 7 or 8 bits of quantization bits per sampling point. . Here, FIG. 3B shows a relationship diagram between the color subcarrier and each sampling point, and each mark on the color subcarrier indicates each sampling point. In FIG. 3B, since the sampling frequency is four times the color subcarrier frequency fsc, four types of sampling points having mutually different phases appear during one cycle of the color subcarrier. The sampling data at these four types of sampling points are respectively A ₁ , B ₁ , C ₁ , D ₁ (or A ₂ , B ₂ , C ₂ , D ₂
etc.), the A/D converter 3 converts the above-mentioned sampling data of 7 bits or 8 bits of quantization bits into A ₁ , B ₁ , C ₁ , D ₁ , A ₂ , B ₂ , C ₂ , _D2 ,
. . . are generated in sequence and output to RAM7.

The RAM 7 has a storage capacity of at least 2H, and is used to rearrange and output incoming sampling data, and outputs the incoming sampling data in a predetermined manner according to the address signal P _A and write control signal P _w . After that, data is written every sampling period 1/fsc, with 1H as a delimiter, and the phases of each sampling data with respect to the color subcarrier of the composite color video signal are in phase with each other (same phase data). comrades as one group, data of group A (A ₁ , A ₂ ...), data of group B B ₁ , B ₂ ..., data of group C C ₁ , C ₂ ..., and data of group D D ₁ , D ₂ ... are generated respectively. Next, RAM7
is the group A to D according to the readout control signal _PR .
Among the group data, for example, the data of the A group and the C group are read out to the D/A converter 8, and the remaining data of the B group and D group are read out to the D/A converter 9.

The D/A converter 8 converts the incoming output data of the RAM 7 into digital data as shown in FIG. 3C and D.
Analog conversion D/A conversion is performed to generate an analog video signal in which two color video signals of 1H and C are arranged, and the signal is passed through the emphasis circuit 10.
Output to FM modulator 11. The FM modulator 11 is
Frequency modulation (FM) of incoming analog video signals
The obtained frequency modulated (FM) analog video signal is output to the recording amplifier 12. Recording amplifier 12
is pulse code modulation (PCM) from input terminal 13.
The digital audio signal (PCM audio signal) and the FM analog video signal are supplied to rotary heads _H1 and _H3 , respectively (FIG. 3E).

Similarly to the above, the D/A converter 9 D/A converts the output data of the RAM 7 as shown in FIG. 3C and D, and two color video signals B and D are arranged within 1H. It generates an analog video signal and outputs it to the FM modulator 15 via the emphasis circuit 14. The FM modulator 15 performs FM modulation on the incoming analog video signal and outputs the obtained FM analog video signal to the recording amplifier 16. The recording amplifier 16 is
The PCM sound signal from input terminal 13 and the above
FM analog video signals are supplied to rotary heads _H2 and _H4 , respectively (Fig. 3E).

Here, the rotating heads H ₁ , H ₂ and H ₃ , H ₄ are respectively attached to a rotating head drum (not shown) so as to face each other by 180°. For this reason, for example, during a period corresponding to the first field of the composite color video signal, the rotating heads _H1 and _H2
A recording track (hereinafter referred to as a first recording track) of analog video signals, etc. corresponding to data of groups B and C, and a recording track of analog video signals (referred to as a second recording track) corresponding to data of groups B and D. A total of two recording tracks (referred to as tracks) are simultaneously recorded on magnetic tapes (not shown), and during a period corresponding to the next one field, the first and second tracks are recorded by rotating heads H' and _H4 . Two recording tracks are simultaneously recorded on the magnetic tape.

By repeating the above operations, the composite color video signal is eventually converted into analog video signals corresponding to the two systems of pseudo component signals and recorded. In this case, NTSC
Taking the method as an example, the band required to transmit analog video signals for each system is 3.58MHz ((4fsc x 2) x (1/2) = fsc = 3.58MHz).

Next, the operation of the reproduction system of the apparatus of the present invention will be explained with reference to FIG. Here, the rotary heads _H1 and _H3 supply the reproduction signal alternately reproduced from the first recording track on the magnetic tape every field to the switch circuit 19 via the preamplifiers 17 and 18, respectively. , rotating head
H ₂ and H ₄ supply the reproduction signal reproduced from the second recording track on the magnetic tape alternately every field to the switch circuit 22 via the preamplifiers 20 and 21, respectively. The switch circuits 19 and 22 are connected to the rotating heads H ₁ , H ₂ and H ₃ ,
The switch circuit 19 switches the respective output signals of the preamplifiers 17 and 18 and outputs them alternately in response to a switching signal from the input terminal 23 corresponding to the magnetic tape sliding scanning period of each of _H4 . 22 switches the respective output signals of the preamplifiers 20 and 21 and outputs them alternately. As a result, the above A
A continuous reproduction signal corresponding to the data of the group and group C is obtained from the switch circuit 19, and similarly, the continuous reproduction signal corresponding to the data of the group B
A continuous reproduction signal corresponding to the data of the group and the group D is obtained from the switch circuit 22.

The output reproduction signal of the switch circuit 19 is supplied to an FM demodulator 25 and a dropout detector 26 via an equalizer circuit 24, and
The PCM audio signal in the output reproduction signal is outputted to an audio signal processing section (not shown) via the output terminal 27. The FM demodulator 25 FM demodulates the FM reproduced analog video signal in the incoming output reproduced signal and outputs the reproduced analog video signal to the A/D converter 2.
8 and timing pulse generation circuit 29, respectively. The timing pulse generation circuit 29 separates a horizontal synchronization signal from the incoming reproduced analog video signal, and supplies timing pulses P _T1 obtained by waveform shaping the horizontal synchronization signal to the PLL 30 and the control device 31, respectively.

Similarly to the above, the output reproduction signal of the switch circuit 22 is transmitted to the FM demodulator 3 via the equalizer circuit 32.
The PCM audio signal in the output reproduction signal is output to the output terminal 27. FM demodulator 33
outputs the reproduced analog video signal obtained by FM demodulating the FM reproduced analog video signal in the incoming output reproduced signal to the A/D converter 35 and the timing pulse generation circuit 36, respectively. The timing pulse generation circuit 36 supplies the PLL 30 and the control device 31 with timing pulses P _T2 obtained by waveform shaping the horizontal synchronization signal in the incoming reproduced analog video signal.

The PLL 30 generates a pulse signal P 1 ' with a frequency of 4 fsc and a four-phase pulse signal P ₂ ' with a frequency fsc based on the incoming timing pulses P _{T1 and} P _T2 , respectively, and supplies them to the control device 31. On the other hand, a clock circuit 38 having a crystal oscillator 37 generates a reference clock signal _P4 with a frequency of 4fsc to
Output to.

The control device 31 supplies the sampling pulse Ps' generated based on the pulse signal P ₁ ' to the A/D converters 28 and 35, respectively, and also outputs a write control signal.
Pw′ is generated and supplied to the RAM 39.

Further, the control device 31 outputs the pulse signal P ₁ ′ and
Based on P ₂ ′, an address signal P _A ′ is generated and the RAM is
39, and based on the reference clock signal _P4 , the readout control signal P _R ' and the pulse signal
P ₃ ′ is generated and the RAM 39 and D/A converter 40
supply each.

By the way, since the reproduced analog video signals output from the FM demodulators 25 and 33 include time axis errors (jitter), the output pulse signals P ₁ ' and P ₂ ' of the PLL 30 also include jitter. becomes. Therefore, the sampling pulse Ps', write control signal Pw', and address signal P _A ' output from the control device 31 also contain jitter similar to the reproduction signal. For this reason, in the A/D converter 35 and RAM 39, which will be described later, signal processing is performed on signals that each include jitter.
There is no effect of jitter associated with this signal processing. After that, the D/A converter 40 uses the readout control signal _PR ' and pulse signal _P3 ' generated based on the jitter-free reference clock signal _P4 to perform the above operations.
Read digital data from RAM39,
Because of D/A conversion, an analog playback signal containing no jitter is obtained. In this way, compensation for jitter is provided.

The A/D converters 28 and 35 respectively sample the reproduced analog video signal based on the sampling pulse Ps', convert it into output data with, for example, 7 or 8 bits of quantization bits per sampling point, and send it to the RAM 39. Output.

The output data of the A/D converter 28 is composed of the data of the A group and the C group per 1H, while the output data of the A/D converter 35 is composed of the data of the B group and D group per 1H. configured.

The RAM 39 has a storage capacity of at least 2H, and inputs the incoming output data of the A/D converters 28 and 35 to the address signal P _A ′ and the write control signal P _W ′.
write to a predetermined address according to the
One data is extracted from the data of group C, group B, and group D, and according to the readout control signal P _R ′,
Each piece of data is read out to the D/A converter 40 in the order of (A ₁ B ₁ C ₁ D ₁ A ₂ B ₂ C ₂ D _{2 .} . . ).

The D/A converter 40 converts the incoming output data of the RAM 39 into a D/A converter according to the pulse signal P ₃ '.
After conversion, the original composite color video signal is restored and outputted to the output terminal 41.

On the other hand, the dropout detectors 26 and 34
each generates a detection signal when it detects that a dropout has occurred in the incoming playback signal,
Output to the control device 31. In this case, the control device 3
1 stores the digital data from 2H ago, which has the same subcarrier phase as the current horizontal scanning period, into RAM 3.
9 and output to the D/A converter 40. The D/A converter 40 D/A converts the incoming digital data 2H ago and outputs it as a composite color video signal of the current horizontal scanning period to the output terminal 41.
Output to.

Note that the configuration of the device of the present invention is not limited to a configuration in which a composite color video signal is divided into two systems of pseudo component signals and recorded and reproduced as in this embodiment, but a composite color video signal is divided into three or more systems of pseudo component signals. A configuration may be adopted in which recording and reproduction are performed separately into pseudo component signals.

Furthermore, the sampling frequency is not limited to 4fsc, and may be any integral multiple of 2 or more of the color subcarrier frequency.

Furthermore, as shown in FIGS. 1 and 2, the signal processing of the device of the present invention may be performed using a digital circuit or, for example, a charge-coupled delay element (CCD delay element).
Also, like the NTSC system, the PAL system has the regularity of in-phase sampling points for color subcarriers, so the device of the present invention can be used.
Of course, the present invention can also be applied to PAL-based composite color video signals.

Effects of the Invention As described above, according to the present invention, a composite color video signal is converted into a plurality of systems of pseudo component signals and recorded on a magnetic recording medium, and the reproduced pseudo component signal from the magnetic recording medium is converted into the original composite color video signal. Since I made it multiplex into a color video signal,
It has many features such as:

Since the composite color video signal is divided into multiple systems of pseudo component signals, the required band per system can be reduced, and the overall video band can be sufficiently wide to obtain high resolution. Since the signal is recorded and reproduced simultaneously, the reproduction system of the apparatus of the present invention does not require a field memory or the like for restoring a plurality of systems of pseudo component signals to a composite color video signal.

A special color process circuit is not required for both the recording system and the playback system of the VTR, and guard bandless recording can be handled using only the azimuth head.

Since single-frequency recording is possible, it is possible to record and reproduce carrier color signals that do not generate spurious interference and are stable against time axis errors (jitter).

[Brief explanation of the drawing]

FIGS. 1 and 2 are block system diagrams showing an embodiment of the recording system and reproducing system of a color video signal magnetic recording apparatus and a magnetic recording/reproducing apparatus according to the present invention, respectively;
3A to 3E are explanatory diagrams of the operation of the block system shown in FIG. 1. 1...Composite color video signal input terminal, 2...
AGC circuit, 3, 28, 35...A/D converter,
4, 29, 36...timing pulse generation circuit,
5,30... Phase rocket loop (PLL), 6,31... Control device, 7,39...
Random Access Memory (RAM), 8, 9,
40...D/A converter, 10,14...Emphasis circuit, 11,15...FM modulator, 12,1
6... Recording amplifier, 13... PCM audio signal input terminal, 17, 18, 20, 21... Preamplifier,
19, 22... Switch circuit, 23... Switching signal input terminal, 24, 32... Equalizer circuit, 2
5, 33...FM demodulator, 26, 34...Dropout detector, 27...PCM audio signal output terminal, 37...Crystal oscillator, 38...Clock circuit, 41...Composite color video signal output terminal , H ₁
~ _H4 ...Rotating head.

Claims (1)

[Claims] 1. Sampling data obtained by sampling a composite color video signal at a sampling frequency n·fsc (where n is an integer of 2 or more, and fsc is the color subcarrier frequency of the composite color video signal) is converted into an analog An A/D converter that outputs digital conversion, and a group of sampled data of each 1/fsc that has the same phase with respect to the color subcarrier of the composite color video signal within one horizontal scanning period. Converts into n types of sampling data groups in total, and further combines these n types of sampling data groups in series, divides them into m (where m is an integer satisfying 2≦m≦n) systems, and outputs them in parallel. m-system D/A converters for separately digital-analog converting the m-system sampling data groups, and frequency modulation of each output analog video signal of the m-system D/A converters to generate magnetic Forming and recording m tracks separately and simultaneously on a recording medium.
What is claimed is: 1. A color video signal magnetic recording device comprising: a system recording means; 2 An A/D converter that samples the composite color video signal at a sampling frequency n·lsc (where n is an integer of 2 or more, and fsc is the color subcarrier frequency of the composite color video signal) and outputs the sampler obtained by analog-to-digital conversion. a D converter, and a total of n types of sampling in which sampling data of each 1/fsc having the same phase with respect to the color subcarrier of the composite color video signal are grouped as one group within one horizontal scanning period. means for converting into a data group, further combining the n types of sampling data groups in series in group units, dividing into m (where m is an integer such that 2≦m≦n) systems and outputting them in parallel; m systems of D/A converters that separately digital-to-analog convert the sampling data groups of the systems, and each output analog video signal of the m systems of D/A converters is frequency-modulated and recorded on a magnetic recording medium. Create and record tracks separately and simultaneously
m systems of recording means, m systems of reproducing means for outputting reproduced signals obtained by reproducing previously recorded signals of the magnetic recording medium from m tracks separately and simultaneously; m systems of A/D converters that sample at a demodulated sampling frequency n·fsc' (where fsc' is the color subcarrier frequency of the reproduced signal) and output m systems of reproduced sampling data in parallel; Each output sampling data of m systems of A/D converters is stored respectively to form a total of n types of digital signal groups, and each reproduced sampling data is extracted one by one from each group in the original order and serialized. 1. A color video signal magnetic recording and reproducing apparatus comprising: means for outputting the extracted reproduced sampling data to digital-to-analog conversion to restore the original composite color video signal.