JPH02132601A - Rotary head type vtr - Google Patents

Abstract

PURPOSE:To rotate a drum at constant revolution speed, and to decrease the band of a recording signal by successively recording signals in an NTSC system, etc., as the recording signal at one channel, and recording a high-vision signal after converting it into the recording signal at plural channels. CONSTITUTION:A period Tf for four heads H1 to H4 to make contact with a tape T is (1/60) seconds, and the phases of the period for the respective heads to make contact with the tapes of the respective heads deviate by 90 deg. respectively. When the color video signal in the NTSC system or a PAL system is recorded, the recording signals for one field are successively supplied to the heads H1 to H4. When the high-vision signal is recorded, the high-vision signal is converted into the recording signal at plural channels, and the signals for 1/3 fields are three-fold time-base-expanded to be a length for the field period Tf. Thus, the revolution speed of the drum are made constant, and the band of the recording signal is decreased.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a rotary head type VTR for recording video signals such as NTSC system and PAL system and high-definition signals using the same head and tape mechanism. Regarding.

[Summary of the invention]

The present invention is a rotary head type VTR capable of recording both NTSC and PAL color video signals and high-definition signals, in which four 90'' heads are arranged at a frequency 1.5 times the frame frequency. The tape is rotated at a rotational speed of By recording at a constant speed, the drum always rotates at a constant rotation speed, and the band of the recording signal is reduced.

(Prior Art) The introduction of high-definition broadcasting is being considered, and transmission systems that compress the band of high-definition broadcast signals have been proposed. Therefore, a VTR capable of recording and reproducing high-definition broadcast signals or their band compression signals (for example, the MUSE signal described in Japanese Patent Application Laid-Open No. 60-86994)
are being considered. High-definition broadcasting signals have 6 to 8 times more information in the baseband than NTSC signals, and in the case of MUSE signals, they have about 2.5 times more information than NTSC signals. have.

As a conventional high-vision V T'R, several systems have been considered as listed below.

In the first method, as shown in FIG. 7A, heads Hl and H2 are provided on the drum D at a spacing of 180 degrees, and the rotational speed of the drum D is set to 3600 rpm, which is twice the frame frequency.
+. Therefore, 1 field signal is 2
Recorded as a book track. In the heads H1 and H2, the longitudinal direction (so-called azimuth) of each magnetic gap is shifted by a predetermined angle to reduce crosstalk from adjacent tracks. In the second method, as in FIG. 7A, heads H1 and f{2 are provided on the drum D at a spacing of 180 degrees, and the rotational speed of the drum D is set to 540 Orpm, which is three times the frame frequency.
The signal of one field is recorded as three tracks.

In the third method, as shown in FIG. 7B, four heads consisting of a pair of heads H1 and H2 and a pair of heads H3 and H4 facing each other at 180 degrees are provided on the drum D, and the frame frequency is 180 Orpm. This rotates the drum D. The heads H1 and H2 have the same azimuth, the heads H3 and H4 have the same azimuth, and the azimuths between these two heads are different so that the azimuths are different between adjacent tracks. Head H1 and H
3 forms two parallel tracks at the same time, and the head H
2 and H4 simultaneously form two parallel tracks.

The fourth method is as shown in FIG. 7C, as shown in FIG.
diameter, e.g. 60~8o mm, larger diameter e.g. 1
Heads H1 and H2 facing each other by 180' are provided on a drum D' having a diameter of 50 to 160. Drum D'
The rotation speed is 1800 rpm.

In the fifth method, as shown in FIG. 7D, six heads consisting of heads H1, H2, H3, H4, H5, and H6 facing each other at 180 degrees are provided on the drum D, and a frame The drum D is rotated at a frequency of 180 rpm. Heads H1, H5, and H4 have the same azimuth so that adjacent tracks have different azimuths, and head H
3, the azimuths of H 2 and H 6 are the same,
The azimuth is different between these three heads. Heads H1 and H2 form two parallel tracks, and heads H3 and H4 form three parallel tracks.

[Problem to be solved by the invention]

Even if high-definition broadcasting starts in the future, conventional television broadcasting will not disappear immediately, and high-definition and NTS
A VTR that can be used both for existing systems such as the C system is preferred. Each of the above-mentioned methods has the following problems from the point of view of dual use.

In the first method (FIG. 7A) and the second method, NTSC signals can be recorded by changing the rotation speed of the drum D to 180 rpm. Although it has the advantage of requiring only two rotating heads, in the case of high-definition video, high-speed rotation of the drum D is required, a switch for changing the drum rotation speed is required, and furthermore, heads H1 and H2 are required for recording. The frequency of the recorded signal becomes higher, and advanced circuit technology is required.

In the third system (FIG. 7B), dual use is possible by recording the NTSC system signal using two opposing heads among the four heads.

However, the heads H1 and H2 or H3 and H4, which are 180° opposed to each other, have the same azimuth. For this reason, when recording to suppress crosstalk from adjacent tracks using azimuth loss, heads with different azimuths, such as H
1 and H4 must be used. Head H1 and H4
Since the facing interval is slightly deviated from 180 degrees, problems occur both in the scanning direction and the height direction of the head.

In the fourth method (Fig. 7C), the number of rotations of the drum D' is 18
By changing to 0Orpm, it is possible to record an NTSC signal. However, since the diameter of drum D' is large, there is a disadvantage that the VTR becomes large.

The fifth method (FIG. 7D) has problems such as the fact that the number of heads is too large, six, and it is difficult to make the characteristics of these heads uniform.

In the above system, 180m opposite heads H1 and H2
The first and second methods using the four heads H1~
It can be said that the third method of performing multi-track recording using H4 is easy to implement in practice. However, no method has been proposed that can solve both problems.

Therefore, it is an object of the present invention to provide a rotary head type VTR that can be used for both NTSC signals and high-definition signals, which solves the above-mentioned problems. That is, the present invention is a rotary head type VTR with a constant drum rotation speed, a reduced recording signal band, and four heads.

[Problem to be solved by the invention]

In this invention, the table T is set at an angle slightly larger than 270°.
Four heads Hl-H4 are arranged at an angular interval of 90' on a drum D rotating at a rotational frequency of 1.5 times the frame frequency, and the first video signal is
Circuits 2, 3, 4 forming the first recording signal of the channel
and a circuit 24 that expands the time axis of a second video signal having a larger amount of information than the first video signal, and converts the second video signal into a second recording signal of multiple channels;
25 to 30, 31, 32, and 33; switch circuits 5 to 8 for selecting the first recording signal and the second recording signal; and first recording for the four heads H1 to H4. circuits 5 to 8 that sequentially supply signals; circuits 46 to 49 that supply second recording signals to the three heads scanning the tape T among the four heads H1 to H4; is provided.

[Effect]

The period T'' during which the four heads H1 to H4 are in contact with the tape T is (1/60) second, and the phase of the period during which each head is in contact with the tape is shifted by 90 degrees. NTSC method or P
When recording color video signals of the AL system, recording signals of one field at a time are sequentially supplied to the heads H1-H4. That is, recording signals are supplied to the heads in the order of heads H1, H4, H3, and H2, and one field of signals is recorded as one track.

When recording a high-definition signal, the high-definition signal is converted into a recording signal of multiple channels, and (1/3
) The signal for each field is time-expanded three times to have a length of field period T[.

Since these time-axis expanded signals overlap, they are supplied to three heads scanning the table T at the same time. Therefore, a recording signal obtained by expanding a (1/3) field signal to the length of one field period is recorded on the tape T as one track.

In this invention, the rotation speed of the drum can always be kept constant.

In addition to converting into recording signals of multiple channels,
Since time axis expansion processing is performed, the frequency of the recording signal does not become high.

〔Example〕

An embodiment of the present invention will be described below.

FIG. 1 shows the configuration of the recording circuit, and FIG. 2 shows the arrangement of the rotary head. In Figure 2, D is 40~60~
has a diameter of 1.5 times the frame frequency (2 7 0
This is a drum that rotates at a speed of 0 rpm) in the direction of the arrow. The rotational frequency of the drum D is constant when recording an NTSC signal and when recording a high-definition signal. The peripheral surface of this drum D is (270°+α)(270°
The magnetic tape T is wound at a winding angle θ of ”: effective portion, α: overlapping portion).The magnetic tape T is fed at a constant speed in the direction of the arrow.Drum D
Above, four heads H1, H2,
H3 and H4 are provided. Heads H1 and H3 have the same azimuth, heads H2 and H4 have the same azimuth, and the two pairs have different azimuths.

In FIG. 1, 1 is an input terminal to which an NTSC color video signal is supplied. The color video signal is supplied to a video signal processing circuit 2, where it undergoes processing such as pre-emphasis, and the output signal of the video signal processing circuit 2 is supplied to an FM modulation circuit 3. The FM modulation circuit 3 subjects the color video signal to FM modulation. The output signal of the FM modulation circuit 3 is supplied to one input terminal a of each of the switch circuits 5, 6, 7, and 8 via the recording equalizer circuit 4.

Switch circuits 5 to 8 select a first recording signal formed from an NTSC signal and a second recording signal formed from a high-definition signal, and send the first recording signal to heads H1 to H4. Supply sequentially. Switch circuit 5~
8 is controlled by a control signal synchronized with the rotational phase of the heads H1 to H4.

Input terminals a of the switch circuits 5 to 8 are supplied with recording signals formed from NTSC signals, input terminals C are supplied with recording signals formed from high-definition signals, and input terminals b are supplied with recording signals formed from high-definition signals. No recording signal is supplied. The output signals of switch circuits 5 to 8 are sent to recording amplifiers 9, 10, 1.
The recording signal is supplied to each of the heads H1-H4 via 1 and 12 and a rotary transformer (not shown), and a recording signal is recorded on the magnetic tape T.

FIG. 3 shows the timing at which the heads H1 to H4 contact the tape T. The head H1 has 27 rotations in one rotation.
It comes into contact with the tape T during the period Tf of the rotation angle of 0°, and does not come into contact with the tape T during the period of the rotation angle of 90°. Head rotation speed is 270
Orpm, the period Tf is (1/60) seconds. Similarly, the other heads H2 to H4 are in contact with the table T for a period of Tf, and the heads H1 to H4 are
Until then, the phases of the contact periods with the tape are shifted by 90°.

One field F1 of the first recording signal formed from the NTSC color video signal is input to the input terminal a of the switch circuit 5 during a period Tf during which the head H1 is in contact with the tape T.
The signal is supplied to the head H1 via the head H1, and is recorded on the tape T as one track. The next field F2 is supplied to the head H4 via the input terminal a of the switch circuit 8,
It is recorded on the tape T as one track. Field F3 is selected by the switch circuit 7 and supplied to the head H3 during the period when the head H3 is in contact with the tape T, and field F4 is selected by the switch circuit 6 and supplied to the head H3 during the period when the head H2 is in contact with the tape T. be done. below,
A similar operation is performed, and each field is sequentially recorded as one track on the tape T, as shown in FIG.

A high-definition signal (baseband signal or MUSE signal) is supplied from a human power terminal 21 to a video signal processing circuit 22 . In the video signal processing circuit 22, in the case of a baseband component, a time division multiplexed signal of a luminance signal and a chrominance signal is formed, and in the case of a MUSE signal, a horizontal synchronization signal of negative polarity is added.

The output signal of the video signal processing circuit 22 is sent to the A/D converter 23
and converted into a digital signal. The output signal of the A/D converter 23 is sequentially supplied to six time axis expansion circuits 25, 26, 27, 28, 29, and 30 by a switch circuit 24. The switch circuit 24 is provided to sequentially supply signals of 1/3 fields to the time axis expansion circuits 25 to 30. Each of the time axis expansion circuits 25 to 30 has a memory having a capacity capable of storing 1/3 field worth of data, and has a frequency of 1/3 of the write clock of the memory.
A read clock with a frequency of 73 is used to perform three-fold time axis expansion.

The output signal of the time axis expansion circuit 25 is supplied to the input terminal a of the switch circuit 31, and the output signal of the time axis expansion circuit 28 is supplied to the input terminal d of the switch circuit 3l. The output signal of the time axis expansion circuit 26 is input to the input terminal b of the switch circuit 32.
The output signal of the time axis expansion circuit 29 is supplied to the input terminal e of the switch circuit 32. Time axis expansion circuit 2
7 is supplied to the input terminal C of the switch circuit 33, and the output signal of the time axis expansion circuit 3 is supplied to the input terminal f of the switch circuit 33.
A zero output signal is provided. These switch circuits 31
, 32, and 33 are controlled by control signals synchronized with the rotational phase of the head.

Three channel signals are generated at the outputs of the switch circuits 31, 32, and 33. A signal obtained from the switch circuit 31 is supplied to the D/A converter 34 and converted into an analog signal. The output signal of the D/A converter 34 is supplied to a video signal processing circuit 35, and the output signal of the video signal processing circuit 35 is supplied to an FM modulation circuit 36. The video signal processing circuit 35 performs processing such as pre-emphasis, and N
Video signal processing circuit 2 installed in TSC recording system
It is similar to . The output signal of the FM modulation circuit 36 is supplied to a recording equalizer circuit 37.

As mentioned above, since the time axis is expanded before being FM modulated, the frequency of the signal becomes 173. Therefore, originally 8
．． The 1MHz, -6dbO roll-off signal (MUSE signal) becomes a 2.7M7, -6db rolloff signal, and the normal NTSC signal (4.2MHz during recording).
, -3db) is similar in frequency.

Therefore, the recording amplifiers 9 to 12 can be used in the 7 to 10 MHz band at most.

Regarding the output signal of the switch circuit 32, a D/A converter 38, a video signal processing circuit 39, an FM modulation circuit 40, and a recording equalizer circuit 4l are provided. switch circuit 3
Regarding the output signal No. 3, a D/A converter 42, a video signal processing circuit 43, an FM modulation circuit 44, and a recording equalizer circuit 45 are provided. A recording signal generated by the recording equalizer circuit 37 is supplied to input terminals a of switch circuits 46, 47, 48, and 49, respectively. A recording equalizer circuit 41 is connected to the input terminal b of these switch circuits 46 to 49.
output signals are supplied to these switch circuits 46 to 4.
The output signal of the recording equalizer circuit 45 is supplied to the input terminal C of the recording equalizer circuit 9 .

Three channels of recording signals are distributed to four heads H1 to H4 by switch circuits 46 to 49. Output signals of switch circuits 46-49 are supplied to input terminals C of switch circuits 5-8, respectively. When recording high-definition signals, the switch circuits 5 to 8 always select the input terminal C.

The output signals of the switch circuits 5 to 8 are recorded on the table T by the heads H1 to H4.

Regarding the recording operation of high-definition signals, Figures 5 and 6
This will be explained with reference to the figures. Similar to FIG. 3A, FIG. 5A shows the period during which the four heads H1 to H4 are in contact with the table T. FIG. 5B shows the expansion operation of the time axis expansion circuits 25 to 30, and F11, F12, and F13 indicate signals having a length of 173 of one field F1. Similarly, F
it, Fi2, and Fi3 each indicate signals obtained by dividing the l field Fi into three.

For each memory of the time axis expansion circuits 25 to 30, 1/
Three fields of digital signals are sequentially written and then read out with a read clock having a frequency 173 times the frequency of the write clock. Therefore, a, b, cSd,
As shown in ..., the length Tf (i.e., 1760
A digital signal whose time axis has been expanded to (seconds) is obtained. These time-axis expanded signals are sequentially recorded on the tape T by the heads H1 to H4, and a track pattern as shown in FIG. 6 is formed on the tape T.

Continuous A/D with fields F1, F2, F3, etc.
The output signal of the converter 23 is converted to 1/1 by the switch circuit 24.
Three fields are sequentially supplied to time axis expansion circuits 25 to 30. 3 by each of the time axis expansion circuits 25 to 30.
The signals a, b, c, shown in FIG. 5B, whose time axis has been expanded twice,
d, ... are human power terminals a of switch circuits 31 to 33
- supplied to f.

The switch circuit 31 alternately selects the input terminals a and d every period Tf, and the switch circuit 31 selects (a, a, g
, . . . ) and a continuous signal whose time axis has been expanded is generated. The switch circuit 32 connects the input terminal b every period Tf.
and e are selected alternately, and from the switch circuit 32, (b
, e, h, . . .), a continuous signal whose time axis has been expanded is generated. The switch circuit 33 alternately selects the input terminals C and r for each period Tf, and the switch circuit 33 generates a continuous signal whose time axis is expanded as (c, f, i, . . . ). do. These switch circuits 31,
The three-channel signals obtained from 32 and 33 undergo recording processing and are supplied to human power terminals a, b, and c of switch circuits 46, 47, 48, and 49, respectively.

The switch circuits 46 to 49 select one of the three channels of recording signals in synchronization with the period during which the heads H1 to H4 are in contact with the tape, respectively. For example, the switch circuit 46 selects the input terminal a, and a recording signal formed from the signal a is recorded on the tape T by the head Hl. Next, the switch circuit 46 selects the input terminal b, and a recording signal formed from the signal e is recorded on the tape T by the head H1.

Furthermore, next, the switch circuit 46 selects the input terminal C, and a recording signal formed from the signal 1 is recorded on the table T by the head H1. Other switch circuits 47, 4, 4
9, like the switch circuit 46, input terminals a, b, c
Select sequentially. However, the switching phase is shifted by 90 degrees.

Switch circuits 5 to 8 always select input terminal C when recording high-definition signals.

As described above, a recorded signal can be converted into a high-definition signal by performing time-axis compression processing instead of time-axis expansion, and by performing processing in the reverse order of recording.

Note that the time axis expansion circuit is not limited to having a memory of (1/3 x 6 = 2 fields) as in the above-mentioned embodiment, but may have a capacity of at least (1/3 x 5 = 573 fields). .

Furthermore, time axis expansion processing may be performed using a memory provided for signal processing during variable speed playback.

Furthermore, the recording signal channels may be four channels corresponding to the heads H1 to H4, respectively.

〔Effect of the invention〕

In this invention, the frequency of the recording signal is lowered by time axis expansion, and the recording amplifier similar to that used in conventional VTRs can be used as the recording amplifier. Further, according to the present invention, there is no need to switch the rotational speed of the drum when recording a signal of the NTSC system or the like and a high-definition signal. Therefore, there is no need for a switch to change the number of rotations of the drum, and it is easy to optimize the rotary head mechanism consisting of the tape, drum, etc., and there is also the advantage that a single drum servo system is required.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a schematic diagram showing the head arrangement of this embodiment, and the third and fourth circles.
The figure shows a timing chart and a route map used to explain the operation when recording an NTS C color video signal, and Figures 5 and 6 show a timing chart and abbreviation used to explain the operation when recording a high-definition signal. 7 is a schematic diagram used to explain a conventional rotary head type VTR. Explanation of main symbols in the drawings Hl-H4: Head, T: Table, 1: NTSC color video signal input terminal, 3, 3
6, 40, 44: FM modulation circuit, 21: High-definition signal input terminal, 25 to 30: time axis expansion circuit. Agent Patent Attorney Masatoshi Sugiura

Claims (1)

[Claims] A tape is wound at an angle slightly larger than 270°, and four heads are provided at angular intervals of 90° on a drum rotating at a rotation frequency 1.5 times the frame frequency. , means for forming a first recording signal of one channel from the first video signal; means for converting the second video signal into a plurality of channels of second recording signals; switch means for selecting the first recording signal and the second recording signal; , means for sequentially supplying the first recording signal; and means for supplying the second recording signal to the three heads scanning the tape among the four heads. A rotating head type VTR characterized by: