JPH01291593A - Vtr of helical scan system - Google Patents

Abstract

PURPOSE:To effectively use a magnetic tape and to attain the making of a signal into a wide band area by recording a FM-modulated luminance signal component on the magnetic tape by a first rotary head and recording a low-pass conversion chrominance signal component on which an audio signal is superposed by a second rotary head. CONSTITUTION:A color video signal is separated to a luminance Y signal and a chrominance C signal at a YC separation circuit 1, and the luminance signal component is converted to an FM modulation wave of low carrier wave at an FM modulation circuit 2, and is supplied to a Y head 4. Meanwhile, the chrominance signal component is frequency-converted to a low-pass side for the luminance signal component at a low-pass conversion circuit 5, and is supplied to a C head 8 after a digital audio signal is superposed as a bypass signal at a mixing circuit 6. The C head 8 is provided for the Y head 4 by separating by recording track width by the Y head 4, and is rotated integrally on the same cylindrical plane. Also, each gap of the Y head 4 and the C head 8 is provided with appropriate azimuth angle difference with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a helical scan type VTR, and more particularly to a helical scan type VTR which is basically a one-head type.

BACKGROUND TECHNOLOGY 1 Head helical scan type VTRs have the advantage of being able to record at high frequencies even if the rotating drum has a small diameter (half the diameter of the two-head type).
As shown in FIG. 6, it is necessary to provide a guard width between tracks on the recording tape pattern, which has been an obstacle to high-density recording on the tape.

In addition, in conventional VTRs, an NTSC color video signal is separated into a luminance signal component and a color signal component, and the luminance signal component is subjected to FM modulation. Since these signals were recorded on a magnetic tape in a superimposed manner, there was a limit to the wideband recording of video signal components and color signal components.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a helical scan type VTR that makes effective use of magnetic tape and enables broadband recording video signals and color signals. do.

The helical scan type VTR according to the present invention has a first rotary head and a same cylindrical surface that is spaced a predetermined distance from the first rotary head in the direction of the rotational axis of the head and has a predetermined azimuth angle difference. It has a second rotary head that rotates integrally with the upper part, separates the color video signal into a luminance signal component and a color signal component, modulates the luminance signal component with FM, converts the color signal component to low frequency, and converts the color signal component to low frequency. An audio signal is superimposed on the converted color signal component, and the FM-modulated luminance signal component is recorded on a magnetic tape by a first rotating head, and the low-frequency converted color signal component with the audio signal superimposed is recorded on a magnetic tape by a second rotating head. The structure is as follows.

Further, the helical scan VTR according to the present invention has a magnetic recording system in which a frequency-converted color signal component obtained by separating and frequency converting a color video signal and an original luminance signal component are recorded on mutually adjacent tracks by a cross-azimuth head. When reproducing a tape, the luminance signal component read by the first rotary head is FM demodulated, and the first rotary head is spaced a predetermined distance from the first rotary head in the rotational axis direction of the head and at a predetermined azimuth angle. The color signal components read by a second rotary head rotating integrally on the same cylindrical surface with a difference are frequency-converted, and the FM-demodulated luminance signal component and the frequency-converted color signal component are mixed. The configuration is such that it is output as a reproduced color video signal.

Example Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram showing the circuit configuration of a recording system of a helical scan type VTR according to the present invention.

In the figure, an NTSC color video signal is separated into a luminance (Y) signal component and a color (C) signal component in a YC separation circuit 1. The separated luminance signal component is sent to the FM modulation circuit 2.
is converted into a low carrier FM modulated wave (for example,
sync chip 5.6MHz, white peak 7MHz)
. The FM-modulated luminance signal is supplied to a Y head 4 as a first rotary head via a rotary transformer 3 and recorded on a magnetic tape (not shown).

On the other hand, the frequency of the separated color signal component is converted to the lower frequency side with respect to the luminance signal component in the low frequency conversion circuit 5. At this time, set the low frequency conversion color signal frequency to 1 MHz or more, for example 1
．． The frequency is set to around 5 MHz, and two frequencies C1 and C2, which differ for each field, are set as described in detail later. This two-frequency CI.

The switching of C2 is performed in synchronization with a switching pulse generated in the switching pulse generation circuit 9 in synchronization with a vertical synchronization signal separated and extracted from the color video signal. This low-frequency conversion color signal is superimposed with a digital audio signal, which will be described later, as a bias in a mixing circuit 6, and then supplied to a C head 8 as a second rotary head via a rotary transformer 7, where it is recorded on a magnetic tape. .

At this time, the vertical synchronizing signal is recorded on the track so that it is located near the end of one track. This is 1/2 of the conventional
This process is different from that used in inch VTRs, in which a luminance signal and a low frequency conversion color signal are recorded in a superimposed manner. The analog audio signal is digitized by the A/D converter 10, then converted into a predetermined format signal by the signal processing circuit 11, and supplied to the mixing circuit 6.

A Y head 4 and a C head 8 are mounted adjacent to each other on a rotating drum (not shown), and as shown in FIG. (Y) Rack) and rotate integrally on the same cylindrical surface. In addition, Y head 4 and C
Each gap of the head 8 has an appropriate azimuth angle difference from each other. And the diameter of the rotating drum is 24 [fl11
1], the rotation speed is 59, 94 [rps], and 1
Record the field/track. Note that when winding the tape around the rotating drum, the angle is not 360' but 330''.
If this is the case, it is possible to record the video signal period excluding the V blanking period in one field.

The magnetic tape used is DAT (Digital Audio Tape Recorder) cassette tape (tape width 3.
81mm, tape length 58680a+m), and the relative speed between the tape and head was approximately 4°5 rn/5cCs.
FIG. 3 shows an example of a tape pattern according to this recording method designed to have a recording time of about 20 minutes.

If the DAT standard is applied to the digital audio signal superimposed on the low-frequency conversion color signal, the tape winding will be approximately 20 mm square.
It is possible to record continuous two-channel 16-bit audio signals with a track length equivalent to 0'. Since this digital audio signal requires a band of 3.5 MHz, it is recorded at a recording frequency of 4 MHz to 7.5 MHz.

Furthermore, the portion outside the recording section of the digital audio signal is
Let us record a signal corresponding to digital 0.

In addition, as mentioned earlier, two frequencies C1 and C2, which differ for each field, are used as the color signal frequency, for example, C1=1.3413.
MHz (85,25fH), C2=1.4436
When using MHz (91,75f+), as is clear from FIG.
The color signals carried by the Y track will be recorded as different frequencies on both sides of the Y track. These two-frequency carrier color signals C, , C2 are used as pilot signals for tracking servo, which will be described later. Here, by appropriately selecting the azimuth angle of the Y track, interference with the video signal can be eliminated. Note that fH is the horizontal scanning frequency (15734, 26 Hz).

In this way, by recording only the luminance signal component separated from the NTSC composite signal and FM modulated on the Y track, it is possible to record low-frequency conversion color signals, audio FM signals, etc. compared to conventional 1/2-inch VTRs. Because there is no such thing, the lower sideband can be secured sufficiently wide, so in this example, a horizontal resolution of about 500 lines can be expected.

In addition, as the low-pass conversion color signal frequency, 1/2 inch VT
In R, a frequency of about 650K to 750KHz was used, but in this example, by changing this frequency to around 1.5MHz, the band of the color signal component can be made sufficiently wider than before, and a good result can be achieved. You can get results.

In this example, regarding the audio signal, DAT
Although it is assumed that recording is performed as a digital audio signal based on the system, it is also possible to employ an audio FM signal depending on the case.

FIG. 4 is a block diagram showing the circuit configuration of the reproduction system. In the figure, the read output of the Y head 4 is supplied to an HPF (bypass filter) 21 and a synchronous separation circuit 21 via a rotary transformer 3, and is also supplied to a tracking servo system (not shown). The luminance signal component that has passed through HPF20 is FM
After FM demodulation in the demodulation circuit 22, the YC mixing circuit 2
3. In the synchronization separation circuit 22, the horizontal synchronization signal and vertical synchronization signal contained in the read output of the Y head 4 are separated and extracted. The separated and extracted horizontal synchronization signal is supplied to the tracking servo system, and the vertical synchronization signal is supplied to the switching pulse generation circuit 24. The switching pulse generating circuit 24 generates switching pulses at one field period in synchronization with the vertical synchronizing signal.

On the other hand, the read output of the C head 8 passes through the rotary transformer 7
It is supplied to a PF (low pass filter) 25 and an HPF 26. In the LPF 25, color signal components are extracted,
In the HPF 26, audio signal components are extracted. The color signal component that has passed through the LPF 25 is sent to the frequency conversion circuit 2.
7 and converted back into a 3.58 MHz carrier color signal. Here, the carrier color signal frequency input to the frequency conversion circuit 27 is two frequencies Cl + C2 that differ for each field.
(For example, Cl-1, 3413MHz s C2-1,
4436MHz), the frequency conversion circuit 27 converts the two-frequency CI + C2 carrier color signal to 3.58MHz by alternately switching between the two conversion systems in synchronization with the switching pulses generated from the switching pulse generation circuit 24. Convert to a carrier color signal. This 3.58
The MHz carrier color signal is mixed with a luminance signal in a YC mixing circuit 23 and output as a reproduced video signal. HP
The audio signal component extracted at F26 is supplied to an audio processing system (not shown) and subjected to signal processing.

FIG. 5 is a block diagram showing an example of the circuit configuration of the tracking servo system in the reproduction system.

In the figure, during the read output of the Y head 4, in addition to the luminance signal component, two frequencies c and
, c2 are mixed in as adjacent signals. The low frequency component including the carrier color signal of this two-frequency ClIC2 is LP
At F30, it is separated and extracted from the read output of the Y head 4. BPF
(Bandpass filter) 2-frequency C at 31.32
The I and C2 carrier color signals are respectively extracted. After each extracted carrier color signal is rectified by rectifier circuits 33 and 34,
The differential amplifier 35 detects the level difference between the two signals. This difference signal is provided to sample/hold circuit 36. The sample/hold circuit 36 generates a difference signal level in response to a burst gate pulse generated during a burst signal period from a burst gate pulse generation circuit 37 in synchronization with the horizontal synchronization signal separated and extracted by the synchronization separation circuit 21 in the reproduction system. The signal is held and supplied as a tracking error signal to a capstan motor (not shown) that drives the tape.

In this way, the two frequencies C+ and C2, which differ for each field, are used as color signal frequencies, and the level difference between the two frequencies CI and C2 mixed as adjacent signals in the read output of the Y head 4 during reproduction is detected. This makes it possible to servo control the tape feed speed so that the center of the Y head 4 always coincides with the center of the Y track, eliminating the need to provide a special control track, and making effective use of the tape width. Become. Furthermore, by using the value sampled and held in the burst signal portion as a comparison result of the two signals, a stable signal level can be ensured regardless of changes in the color signal level due to the subject.

As described in detail, according to the helical scan type VTR of the present invention, the first rotary head is spaced apart from the first rotary head by a predetermined distance in the direction of the rotational axis of the head, and has the same azimuth angle difference. A second rotary head that integrally rotates on a cylindrical surface is provided, and the luminance signal component obtained by separating it from the color video signal is subjected to FM modulation. By recording the frequency-converted color signal components onto the magnetic tape using a second rotary head, the Y track contains low-frequency converted color signals and audio FM signals similar to those of a conventional 1/2-inch VTR. It is advantageous for high-resolution signal recording because the sideband can be widely used without
Furthermore, the low frequency conversion color signal frequency has been changed from the conventional 1/2 inch V
Since it can be approximately twice that of TR, the color signal band can also be made sufficiently wide.

In addition, by recording the audio signal on the C track in a signal format that acts as a bias for the low frequency conversion color signal frequency,
Since it is no longer necessary to equalize the R channel audio tracks, the tape width can be used effectively, and since an audio head is no longer necessary, the apparatus can be made lower in cost, smaller in size, and lighter in weight.

[Brief explanation of the drawing]

Figure TS1 is a block diagram showing the circuit configuration of the recording system of the helical scan VTR according to the present invention, Figure 2 is a diagram showing the positional relationship between the Y head and C head and the locus of the Y track and C track, and Figure 3 is a diagram showing the DAT. Figure 4 is a block diagram showing the circuit configuration of the playback system, and Figure 5 is a diagram showing the circuit 114 configuration of the tracking servo system in the playback system. FIG. 6, a block diagram showing an example, is a diagram showing a tape pattern of a conventional 1/2 inch VTR. Explanation of symbols of main parts 1...YC separation circuit 2...FM modulation circuit 4...Y head 5...
Low frequency conversion circuit 8...C head 21...
... Synchronization separation circuit 22 ... FM demodulation circuit 2
3...YC mixing circuit 27...Frequency conversion circuit 35...Differential amplifier 36...Sample/hold circuit Applicant
Pioneer Corporation

Claims (2)

[Claims] (1) A first rotary head and a rotary head that is spaced apart from the first rotary head by a predetermined distance in the direction of the rotational axis of the head and with a predetermined azimuth angle difference, and rotates integrally on the same cylindrical surface. a separation circuit that separates the color video signal into a luminance signal component and a chrominance signal component; an FM modulation circuit that FM modulates the luminance signal component; and a FM modulation circuit that performs FM modulation of the luminance signal component; a frequency converting circuit; and a mixing circuit for superimposing an audio signal on the low frequency converted color signal component by the low frequency converting circuit; A helical scan VTR characterized in that signals are recorded on a magnetic tape by the second rotary head. (2) A helical scan method in which a frequency-converted color signal component obtained by separating and frequency converting a color video signal and an original luminance signal component are reproduced from a magnetic tape recorded on adjacent tracks with a cross-azimuth head. V
The TR includes a first rotary head, which is spaced apart from the first rotary head by a predetermined distance in the direction of the rotational axis of the head and has a predetermined azimuth angle difference, and is arranged on the same cylindrical surface. The luminance signal component read by the second rotary head that rotates integrally with the first rotary head is F.
an FM demodulation circuit that performs M demodulation; a frequency conversion circuit that converts the frequency of the color signal component read by the second rotating head; and a frequency conversion circuit that converts the frequency of the luminance signal component demodulated by the FM demodulation circuit and the frequency conversion circuit. A helical scan method V characterized by comprising a mixing circuit that mixes the color signal components and outputs the mixed color signal components as a reproduced color video signal.
T.R.