JPH0492261A - Vtr - Google Patents

Abstract

PURPOSE:To perform post-recording and the recording/reproduction of a signal satisfactorily with configuration by performing the time base compression of a video signal and a PCM audio signal, arranging them within the rotating period of 180 deg. of a rotary drum, and planning the position of arrangement. CONSTITUTION:A tape 18 is wound across the range of adjacent 180 deg. of the rotary drum 16, and the time division multiplexing of the video signal and the PCM audio signal are performed by using every kind of memory, an adder, and servo under the control of a control circuit, and the recording/reproduction is performed with heads 17A, 17B. The time base compression (frame memory 11) of the video signal is performed at every prescribed unit period in accordance with the rotation of 180 deg. of the rotary drum, and the time base compression (frame memory 43) of the PCM audio signal in accordance with the unit period is performed to the length of a margin period generated by the time base compression of the video signal, and the time division multiplexing (adders 14A, 14B) is performed on the signal by arranging before a time base-compressed video signal, thereby, the recording of the PCM audio signal to which the time base compression is applied at a rushing part to the recording medium of the head is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is applicable to, for example, a VTR that records and reproduces HDTV signals.
Regarding.

[Summary of the invention]

The present invention relates to a VTR, and the present invention compresses the time axis of a video signal and a PCM audio signal, arranges these signals within a 180-degree rotation period of a rotating drum, and devises the position of this arrangement, thereby making it simple. This configuration enables after-recording and also ensures good signal recording and playback.

[Conventional technology]

Conventionally, VT records and plays back video signals and PCM audio signals.
In R, for example, the PCM audio signal is frequency multiplexed into a part of the recording signal band, or the 180
A method has been implemented in which the recording medium is wound over a range of more than 180 degrees and a PCM audio signal is recorded in the portion exceeding 180 degrees.

Also, as shown in Figure 8, the winding range of the recording medium is 180 mm.
Although it is possible to perform after-recording using the method of increasing the frequency, when performing after-recording while playing back the video signal, the PCM audio signal recorded on the playback signal of the video signal overlaps, and the playback of the video signal becomes impossible. could not be performed well. It is possible to reduce the overlap by installing a recording amplifier, a playback amplifier, a switch, etc. inside the rotating drum, but it is difficult to reduce the overlap to zero, and the configuration for this would be complicated, making the equipment difficult to operate. It was also a loss of credibility.

This application was made in view of these points, and is intended to enable after-recording with a simple configuration and to perform good signal recording and reproduction.

[Problem to be solved by the invention]

However, among these methods, it is difficult to perform so-called after-recording in the frequency multiplexing method.

[Means to solve the problem]

The first means according to the invention has a rotating drum (16), and a recording medium (
In a VTR, a tape (18)) is wound, and a video signal and a PCM audio signal are time-division multiplexed and recorded and reproduced by heads (17A) (17B) provided on the rotating drum. The video signal is time-axis compressed (frame memory (11)) for each predetermined unit period corresponding to the 180 degree rotation of the rotary drum, and the PCM audio signal corresponding to the unit period is compressed in the time axis of the video signal. Time axis compression (frame memory (43)) L to match the length of the blank period caused by axis compression,
By performing the time-division multiplexing (adders (14A) (14B)) so that the time-axis compressed PCM audio signal is located before the time-axis compressed video signal, at least the above-mentioned This is a VTR in which the time-base compressed PCM audio signal is recorded at the point where the head enters the recording medium.

In a second means, in the first means, a plurality of recording systems each having at least two channels are provided for the PCM audio signal, and the time division multiplexing is arranged so that each of these systems is at an independent position. VT to be performed
It is R.

A third means is a VTR in which, in the second means, each system of the PCM audio signal is arranged at least one system before and after the time-axis compressed video signal.

A fourth means is a shortest recording wavelength (emphasis and FM modulation circuit (134) (13) of the time-base compressed PCM audio signal in the first, second or third means.
B) ) becomes longer than the shortest recording wavelength of the time-axis compressed video signal (recording encoding circuit (44A) (
44B)).

[Operation] According to this, the video signal and the PCM audio signal are compressed on the time axis, and these signals are arranged within the 180 degree rotation period of the rotating drum, and the position of this arrangement etc. is devised. This makes it possible to perform after-recording with a simple configuration, and to perform good signal recording and reproduction.

[Example] By the way, for VTRs that record and play back HDTV signals, such as high-definition signals, especially for consumer equipment, the chroma signal is line-sequentialized, the time axis is expanded/contracted, and time-division multiplexed with the luminance signal, resulting in a so-called TCI signal. It is being considered to perform recording and playback by dividing into multiple channels using a multi-channel head (Japanese Patent Laid-Open No. 19449/1983).
(See Publication No. 4, etc.)

That is, FIG. 1 shows an example of a device applied to such a system. In this figure, (1) is an input terminal for a luminance signal (Y) demodulated from, for example, an HDTV signal, and this terminal (1) The signal from the A/D conversion circuit (2
) are supplied to the line memories (3A) and (3B). Furthermore, (4r) and (4b) are chroma signals demodulated from HDTV signals (color difference signals R-Y: CR, B-Y: C
B) input terminal, this terminal (4r) (4b)
The signals from the A/D conversion circuits (5r) (5b
) are supplied to the line memories (6r) and (6b).

Furthermore, (7) is the synchronization signal separated from the HDTV signal (
Sync), and a signal from this terminal (7) is supplied to the control circuit (8). In this control circuit (8), various control signals and clock signals, which will be described later, are generated in accordance with the reference clock signal supplied from a predetermined reference oscillator (9) and the above-mentioned synchronization signal.

As a result, the signal taken out from the memory (3A) and the signal taken out from the memory (6r) are combined in the adder (10A) and supplied to the frame memory (11), and the signal taken out from the memory (3B) and the signal taken out from the memory (6b) are combined by an adder (IOB) and supplied to the frame memory (11). And this memory (11
) The signal extracted from the D/A converter (12A) (1
2B) through the emphasis and FM modulation circuit (13A
) (13B), and this emphasis and FM
The modulated signal is supplied to an adder (148) (14B).

Further, (40R) (40L) is an input terminal for, for example, stereo left and right audio signals, and this terminal (40R) (
The signal from the A/D conversion circuit (41R) (40L) is
1L) to an audio signal recording processing circuit (42), where conversion into a PCM audio signal, such as adding a predetermined error correction code, is performed. A signal from this processing circuit (42) is supplied to a frame memory (43). Then, the signal taken out from this memory (43) is passed through the recording encoding circuit (44A) (44B) to the adder (14A) (
14B).

The signals from the adders (14A) (14B) are then supplied to the heads (17A) (17B) on the head drum (16) via recording amplifiers (15A) (15B) and recorded on the tape (18). be done. Note that the heads (17A) and (17B) are integrated on each side as described later, and a magnetic gap corresponding to each head is formed in one magnetic head device.

Furthermore, the reference signal from the control circuit (8) is transmitted to the servo circuit (1
9), and the spindle motor (20) of the head drum is driven by the signal from this servo circuit (19). Further, a signal from the servo circuit (19) is supplied to a capstan motor (21), and this motor (21) drives a capstan (22) for transporting the tape (18).

Recording is performed as described above. Note that during reproduction, the above operations are performed in reverse, and, for example, an HDTV signal and stereo left and right audio signals are reproduced.

In this apparatus, for example, when recording a high-definition signal, first the steps A and B in FIG. 2 are performed.

Luminance signal (Y) and chroma signal (RY:
CR, B Y: C8) are the control circuits (8
) is sampled with a clock signal of frequency fA, f, and A/D converted to the memory (3A) (3B)
(6r) Written to (6b).

Here, the frequency fA is, for example, an integer ratio as simple as possible of 74.25MHz, which is the basic clock of high-definition.
In addition, the horizontal frequency of high-definition (fn+=33.75k
Hz), for example, f A--
X74.25=44.55 (MHz)=132Of
, l+. Also, f is selected as 2 of fA.

In other words, this reference oscillator (9
), and the clock signal from this oscillator (9) is supplied to the control circuit (8), so that the clock signal of frequency fA is directly outputted, and the clock signal of each frequency f is output directly. The signal can be output by dividing the frequency of the supplied signal by two.

As a result, the luminance signal (Y) and chroma signal (CRlC
Il) are sampled at 1320 and 330 samples per horizontal scanning line and written to the memories (3A) (3B) (6r) (6b), respectively, as shown in the figures above.

Note that writing is performed using each horizontal synchronizing signal as a start signal, and data is written to the memories (3A) (3B) alternately for each horizontal period.

Furthermore, this written signal is read out with a clock signal of frequency f, thereby expanding or contracting the time axis, and this signal is synthesized by an adder (IOA) (10B), for example, as shown in the above figure, E A so-called Tel signal as shown in FIG.

Here, the clock frequency fc of this Tel signal, the number of horizontal scanning lines per frame, and the number of samples per one horizontal scanning line S are selected as follows.

That is, when forming a Tel signal from the above-mentioned high-definition signal, since the above-mentioned apparatus performs two-channel simultaneous recording, the signal is 1125x1320 LxS 44.55xlO62f.

must hold true, where the value of S is VTR
For example, L=1332.5=
1500 recording format, f,
=29.97 (M7) -88Of□= f.

becomes.

Therefore, the clock signal of this frequency f is the memory (3A)
(3B) (6r) (6b) and
For example, the chroma signal (Ci,
CB), 280 samples of the video screen period are read out, and then 1120 samples of the effective screen period and 100 samples of the synchronization period of the luminance signal (Y) written in the line memories (3A) (3B) are read out. Ru.

As a result, a 2 (A, B) channel Tel signal as shown in the above figure is formed. Note that successive output is performed using every other horizontal synchronizing signal as a start signal, and signals formed by alternate horizontal scanning line signals are simultaneously extracted for each channel. Also, in this case, since the frequency fc is greater than 'A r A, the actual TCT
The length of one horizontal period of the signal is somewhat shorter than twice that of the high-definition signal.

The Tel signals formed in this way are sequentially stored in the frame memory (
11).

The signal written in this frame memory (11) is then read out using a clock signal of frequency fc. In addition, from the frame memory (11), the head (17A) (17B)
The signals of every other horizontal period written in the memory (11) during the first contact running period (first segment) with respect to the tape (18) are sequentially extracted with a clock signal of frequency fc, Successive output is performed so that the signals of every other remaining horizontal period are sequentially extracted during the second (second segment) contact running period. At the same time, this succession is performed continuously in each horizontal period, and the length of one horizontal period of the Tel signal is somewhat shorter than twice that of the high-definition signal as described above, so that the frame memory (11) The total length of the signal read from the head (17A)
(17B) is shorter than the length of each contact running period with respect to tape (18).

This successively output signal is D/A converted, subjected to emphasis and FM modulation, and then supplied to adders (14A) (14B).

On the other hand, the frame memory (43) has an A/D conversion circuit (
41R) (41L) for example 48kHz or 32
A PCM audio signal formed by adding a predetermined error correction code to the signals sampled at 1 and 7 is written using a clock signal of a predetermined frequency fIl. Then, by further supplying a clock signal of a predetermined frequency fE to this frame memory (43), the above-mentioned frame memory (
The total length of the signal read from the head (11)
A) A PCM audio signal corresponding to each scanning period of the head (17A) (17B) is formed in a period shorter than the length corresponding to the length of each scanning period for the tape (18) of (17B). As shown in the following, more and more will be published.

This read signal is sent to the encoding circuit (44A) (44
B), it is converted into a predetermined recording signal and sent to an adder (14).
A) (14B).

That is, in the above-described apparatus, when there is a video signal and a PCM audio signal as shown in FIGS. 3A and 3B, this video signal is transmitted to the tape (18) of the head (17A) (17B)
), the time axis is compressed as shown in Figure C, and the margins created by this compression are filled with the same period of the PCM audio signal as shown in Figure C. The corresponding amount is compressed on the time axis. Further, during this compression, the video signal is placed at the rear of each contact running period, and the PCM audio signal is placed at the front.

Then, these signals are added by an adder (148) (14B) to perform time division multiplexing, and this adder (14A)
) (14B) is sent to the head (17A) (17B
) and recorded on tape (18).

At this time, the frequency f from the control circuit (8) is 60H.
A reference signal of z is supplied to the servo circuit (19), and the head (176) (17B) is rotated at a frequency f, and the tape (18) is transported so that a predetermined track pitch is obtained during this period. will be held.

Therefore, in this device, the head (17A) (17B
) records and reproduces video signals and PCM audio signals during the 180-degree running period, as shown in Figure 4, and the recording medium is wound within a 180-degree range around the rotating drum. By doing so, it is possible to record and reproduce good signals without signal overlap even during after-recording.

Also, since time division multiplexing is performed by arranging the PCM audio signal in front of the video signal, for example, the PCM audio signal is processed at the entry point of the head (17A) (17B) into the tape (18). Recording is performed, and overall good signal recording and reproduction can be performed. In other words, the air film is usually thick at this entry point, resulting in a large spacing loss, making it unsuitable for recording analog video signals. Therefore, as described above, by recording the PCM audio signal in this portion, the influence of spacing loss can be reduced, and overall good signal recording and reproduction can be achieved.

In this way, it is possible to record, for example, a high-definition signal, but according to the above-mentioned device, the video signal and the PCM audio signal are time-axis compressed and
By arranging these signals within an 80-degree rotation period and by devising the position of this arrangement, it becomes possible to perform after-recording with a simple configuration.
This allows good signal recording and reproduction to be performed.

Further, in this device, the head (17A) (17B
) each consist of two heads, which are arranged 180 degrees apart from each other on the rotating drum (16), and on one side of them, the heads (16)
The structure of 7A) (17B) is, for example, as shown in FIG.
) with the other azimuth angle corresponding to the magnetic gap (17b
) are integrally provided with a step equal to the track pitch p of the track pattern formed when the tape is transported at a standard speed, thereby forming one magnetic head device (71). Therefore, in this magnetic head device (71), two inclined tracks are formed at a time, and the rotating drum (
16), four inclined tracks are formed in one rotation, and the recording azimuth angles of the inclined tracks are alternately made different.

As a result, a video signal is recorded on the tape (18) in a recording pattern in which one frame is made up of two revolutions of the rotating drum (70) and four segments (eight tracks) in two channels, as shown in FIG. As described above, recording of PCM audio signals and the like is performed in the range created by compressing the time axis of the video signal.

In other words, in this figure, the PCM is located in the front side of the recording range of the video signal in the head scanning direction, as shown in the figure.
A recording range for audio signals is provided. Here, each track has a wrapping angle of 180 degrees and corresponds to 166.5 horizontal periods, of which 23 horizontal periods (24, 86 degrees) are the recording range of the audio signal. Approximately 1.2 degrees at the front end is used as a margin, and the next 2.0 degrees is used as a preamble section.Continuation <8.
PCM audio signals of the third and fourth channels are recorded at 0 degrees. Furthermore, the next 1.2 degrees is considered the postamble part,
The interval <1.2 degrees is taken as a guard section between audio signals. Further, the next 2.0 degrees is the preamble section, the next <8.0 degrees the PCM audio signals of the first and second channels are recorded, and the subsequent 1.26 degrees is the postamble section.

Further, following this audio signal recording range, a guard section between the audio signal and the video signal for 2 horizontal periods is provided, and in the subsequent 11 or 11.5 horizontal periods, vertical synchronizing signals V, .
Information signals such as V, , AGC reference level, clamp level, etc. are provided, followed by TC of 130 horizontal periods, respectively.
The I signal is recorded as shown according to the distribution described above.

Note that the numbers in the figure indicate the horizontal period numbers, and R and B indicate the chroma signals to be multiplexed. Further, a margin of 0.5 or l horizontal period is provided after the recording range of this TCI signal.

Therefore, according to this device, each PCM audio signal has two
There are two channels each (1st, 2nd, 3rd, and 4th channels), and since the signals of these two channels are recorded independently, it is possible to after-record these signals independently. In addition, in this case as well, there is no fear of overlapping the video signal during after-recording as described above.

Furthermore, when recording two or more PCM audio signals in this manner, at least one system is placed before and after the video signal as shown in FIG. The influence on the analog video signal due to instability of the tape (18) can be eliminated not only at the part where it enters the tape (18) but also at the part where it leaves the tape (18).

Furthermore, in the above-mentioned apparatus, the encoding circuit (44A) (
The shortest recording wavelength of the recording signal of the PCM audio signal converted by the emphasis and FM modulation circuit (13
A) By configuring (13B) to be longer than the shortest recording wavelength of the FM-modulated video signal, the effect of spacing loss can be significantly reduced, resulting in better overall signal recording and playback. It can be performed.

Note that this application applies not only to high-definition VTRs but also to other HDTs.
It can also be applied to recording and reproducing V signals and ordinary video signals.

[Effects of the Invention] According to the present invention, the video signal and the PCM audio signal are compressed in the time axis, and these signals are arranged within the 180-degree rotation period of the rotating drum, and the position of this arrangement is devised. By doing so, it has become possible to perform after-recording with a simple configuration and to perform recording and reproducing of good signals.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an example of a VTR according to the present invention, Fig. 2 is a waveform diagram for explaining the signal, Fig. 3 is a diagram for explaining time axis compression, and Fig. 4 is a diagram of the head and recording signal. 5 is a diagram showing the relationship, FIG. 5 is a diagram showing the configuration of the main parts of the VTR, FIG. 6 is a diagram for explaining the recording pattern, FIG. 7 is a diagram for explaining the recording pattern of another example, and FIG. FIG. 8 is a diagram showing the relationship between a conventional head and recording signals. For example, (1) is an input terminal for a luminance signal demodulated from an HDTV signal, (2) is an A/D conversion circuit, (3A) and (3B) are line memories, and (4r) and (4b) are chroma signals that are demodulated from an HDTV signal. The input terminal of (5r) (5b) is A
/D conversion circuit, (6r) (6b) is line memory, (
7) is the input terminal for the synchronization signal separated from the HDTV signal, (8) is the control circuit, (9) is the reference oscillator, (IOA)
(IOB) is an adder, (11) is a frame memory, (
12A) (12B) is a D/A converter, (13A) (1
3B) is an emphasis and FM modulation circuit, (14A) (
14B) is an adder, (15A) (15B) is a recording amplifier, (16) is a rotating drum, (17A) (17B) is a head, (18) is a tape, (19) is a servo circuit, (
20) is the spindle motor of the rotating drum, (21) is the capstan motor, (22) is the capstan for transporting the tape, (40R) (40L) are input terminals for left and right stereo audio signals, (411?) (41L) is an A/D conversion circuit, (43) is a frame memory, and (44A) (44B) is a recording encoding circuit.

Claims (1)

[Claims] 1. It has a rotating drum, a recording medium is wrapped around the rotating drum in a 180 degree range, and the video signal and the PCM audio signal are time-division multiplexed to the rotating drum. In a VTR configured to be recorded and played back using a head provided, the video signal is time-axis compressed for each predetermined unit period corresponding to the 180 degree rotation of the rotating drum, and the video signal is The time axis of the PCM audio signal is compressed to the length of the blank period generated by the time axis compression of the video signal, and the time axis compressed PCM audio signal is located before the time axis compressed video signal. By arranging the VTR as follows and performing the time division multiplexing, the time-axis compressed PCM audio signal is recorded at least at a portion where the head enters the recording medium. 2. In claim 1, the PCM audio signal is provided with a plurality of recording systems each having at least two channels, and the time division multiplexing is arranged so that each of these systems is at an independent position. VT that was made to be
R. 3. The VTR according to claim 2, wherein the position of each system of the PCM audio signal is arranged at least one system before and after the time-axis compressed video signal. 4. In claim 1, 2, or 3, the shortest recording wavelength of the time-base compressed PCM audio signal is longer than the shortest recording wavelength of the time-base compressed video signal. A VTR made like this.