JPS6352835B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording and reproducing method for recording and reproducing video signals on a recording medium in which a plurality of annular tracks are concentrically formed, and is particularly suitable for use in a video sheet recorder. be.

In a video sheet recorder (hereinafter referred to as VSR), for example, when recording a video signal using the NTSC method, a disk-shaped magnetic sheet is rotated at a speed of 3600 rpm, and a signal for one field is recorded for each rotation. That's what I do. Therefore, a large number of circular tracks are concentrically formed on the recorded magnetic sheet. During playback, each track is played sequentially or in the order according to the program.
In this case, the playback head is configured so that when the playback of one track is completed, it is moved to the next track at high speed. In order to eliminate screen disturbances when the reproducing head moves, the signals of each track are recorded so that the phases of the vertical synchronizing signals are aligned during recording. The reproduction head is moved at high speed during the vertical blanking period to eliminate screen disturbances. In order to match the phase of the vertical synchronization signal of each track, conventionally, a positioning hole is provided at a predetermined position of the magnetic sheet, and a positioning pin is fitted into this hole when the magnetic sheet is attached to the VSR. A method is used in which a reference point is obtained by optically detecting the holes, and rotational phase servo is applied to the magnetic sheet based on this reference point. However, this method requires a step of punching holes in the magnetic sheet, and there is also a problem with the positional accuracy of the holes. Furthermore, it is not desirable to provide holes in the magnetic sheet.

The present invention has been made in view of the above problems, and embodiments of the present invention will be described below with reference to the drawings.

In this embodiment, as shown in FIG.
The innermost track is defined as a reference track 2, and a reference signal containing at least a vertical synchronization signal and a wobbling frequency component is recorded in advance on this reference track 2. In VSR, in order to perform automatic tracking of the head, the head is vibrated in the width direction of the track at a frequency of, for example, 1 KHz during recording and reproduction. Then, by detecting the wobbling component obtained during reproduction and controlling the position of the head based on this detection output, tracking errors due to eccentricity of the magnetic sheet, etc. are corrected. In this embodiment, by providing the reference track 2 as described above,
During recording, the eccentricity of the magnetic sheet is detected by reproducing the reference track 2 prior to recording, and the recording track is formed concentrically by controlling the head according to the eccentricity during recording. There is. Furthermore, phase servo is applied based on the vertical synchronization signal obtained from the reproduced signal of the reference track 2, and auto tracking is performed.

Next, a specific example of a circuit for realizing the above object will be described with reference to FIG.

In FIG. 2, the magnetic sheet 1 is rotated by a motor 3 at a speed of, for example, 3600 rpm. motor 3
A PG (pulse generator) 5 is provided on the shaft 4 of the magnetic sheet 1.
Individual PG pulses are obtained. This PG pulse
is added to the phase comparator 7 through the PG amplifier 6,
It is compared with a vertical synchronization signal, which will be described later. By applying this comparison output to the motor 3 through the motor drive circuit 8, the motor 3 is controlled to a predetermined rotational phase. In addition to the above-mentioned phase servo loop, this motor 3 is provided with a speed servo loop (not shown), and the motor 3 is controlled to a predetermined speed by this servo loop.

The recording/reproducing head 9 is attached to a head arm 10, and this head arm 10 is connected to a drive mechanism 1.
Movement is controlled by 1. This drive mechanism 11 is
When the head 9 records and reproduces a track, the head 9 is operated to wobble at a predetermined frequency in the width direction of the track (in the direction of arrow a), and after the recording and reproduction of one track is completed, the head 9 moves to the next track. Operated to move instantly at high speed. In order to perform the wobbling described above, a wobbling oscillator 12 is provided, and its wobbling signal is applied to the drive mechanism 11 through a drive circuit 13. A variable drive power supply 14 is also provided to move the head 9 between tracks, and its drive voltage is applied to the drive mechanism 11 through an adder 15 and a drive circuit 13.

A video signal S _v to be recorded is input to the input terminal 16 . This signal S _v is applied to the recording processing circuit 17, where signal processing is performed such as, for example, FM modulating the Y signal (luminance signal) and low frequency conversion of the C signal (chroma signal) to a predetermined frequency. This processed signal is applied to the head 9 through the recording amplifier 18 and the REC contact of the recording/reproducing switch 19, thereby being recorded on the reference track 2 of the magnetic sheet 1 or other recording tracks. Above signal
S _v is also applied to a vertical sync separation circuit 20 to separate its vertical sync signal VD ₁ . This signal VD ₁
is applied to the phase comparator 21, the variable delay circuit 22, and the REC ₁ contact of the switch 23. Further, the signal VD ₁ delayed by the delay circuit 22 is output to the switch 23.
Added to REC ₂ contacts.

When the reference track 2 is being played back and when other tracks are being played back, the switch 19 is closed to the PB contact.
The reproduced signal from the head 9 is applied to a wobbling component detection circuit 25 through an amplifier 24, and is also applied to a reproduction processing circuit 26. The detection circuit 26
The detected output is applied to a phase comparator 27 and compared with the wobbling signal from the wobbling oscillator 12. This comparison output is passed through the low-pass filter 28 as a signal representing the amount of eccentricity, as will be described later.
It is written to the memory 29 through the PB contact of the switch 30, the amplifier 31, and the adder 15.
and is applied to the drive mechanism 11 through the drive circuit 13. On the other hand, the reproduction processing circuit 26 demodulates the Y signal from the reproduction signal and frequency converts the C signal to obtain the original video signal. This video signal is output from the output terminal 32, and
The vertical synchronization signal VD ₂ is added to the vertical synchronization separation circuit 33 and extracted. This signal VD ₂ is applied to the PB contact of the switch 23 and also to the phase comparator 21 where it is compared with the signal VD ₁ A.
This comparison output is written to memory 29. The signals S ₁ , S ₂ , and S ₃ are read out from the memory 29 during recording. The delay time of the delay circuit 22 is controlled by the signal _S1 , the drive power supply 14 is controlled by the signal _S2 ,
Signal S ₃ is also applied to contact REC of switch 30. Incidentally, data such as a program for reproducing the recorded tracks, the address of each track, a table of contents, etc. may be recorded in the reference track 2, as will be described later. In that case, the signal obtained from the reproduction processing circuit 26 during reproduction of the reference track 2 is applied to the data detection circuit 34 to detect the above data, and this data is written into the memory 29. Note that the signal _S2 is a signal based on the data, which will be described later.

Next, the operation of the above configuration will be explained.

First, the case where a reference signal is recorded on the reference track 2 of the magnetic sheet 1 will be described.

A reference signal is applied from the input terminal 16, but the content of this reference signal does not matter as long as it includes at least a vertical synchronization signal, except when recording the above data. Therefore, the video signal S _v can be used as a reference signal. First, the switch 19 is closed to the REC side, and the head arm 10 is moved by the voltage of the drive power source 14, so that the head 9 is brought to a predetermined position. Next, when the motor 3 is rotated at a predetermined speed and a signal S _v is input, this signal S _v is processed by a recording processing circuit 17 and then applied to the head 9 via an amplifier 18 and a switch 19 . As a result, one field of signals including one vertical synchronization signal is recorded on the reference track 2. Note that the reference track 2 is the magnetic sheet 1.
It may be formed not only on the innermost periphery but also on the outermost periphery or at other predetermined positions.

Next, a case will be described in which the magnetic sheet 1 on which the reference track 2 is recorded as described above is once removed from the VSR, and then mounted again to record the signal S _v on another recording track.

Since the magnetic sheet 1 in this embodiment does not have any position regulating means such as positioning holes, the magnetic sheet 1 is placed in a different state each time it is mounted. Therefore, if, for example, the magnetic sheet is removed after recording on several tracks and then reattached to perform recording without considering the processing according to the present invention, recording will be performed. The position of the vertical synchronization signal recorded on each track differs from time to time. This type of VSR uses the reproduced vertical synchronization signal as a reference during playback, and applies phase servo by comparing the phase of this and the PG pulse, so if the position of the vertical synchronization signal differs for each track,
The phase servo is disturbed during reproduction, and the screen is also disturbed when the head 9 moves. In order to solve this problem, for example, a method can be considered to delay the PG pulse according to the deviation of the vertical synchronization signal, but since the PG pulse contains jitter,
If this is delayed, the servo characteristics will deteriorate.

Furthermore, if the magnetic sheet 1 is eccentric, the eccentric point will be different each time recording is performed, so that it is not possible to form all tracks concentrically.

In this embodiment, in order to solve these problems, a reference signal recorded on a reference track is used. First, before recording the signal _Sv , the reference track 2 is reproduced. At this time, switch 1
9 and 30 are closed to the PB side, and switch 23 is closed.
Closed to REC ₁ side. Further, a signal S _v is applied to the input terminal 16. As a result, the signal VD 2 is obtained from the reproduced signal of the head 9 by the vertical synchronization separation circuit 33, and the signal VD ₂ is obtained from the signal S _v by the vertical synchronization separation circuit 2.
0 gives the signal VD ₁ . This signal VD ₁ is applied to the phase comparator 7 via the switch 23. Therefore, the motor 3 is subjected to phase servo with reference to the signal _VD1 of the signal _Sv . Also this signal
VD ₁ and VD ₂ are compared by a phase comparator 21. When the phase servo is locked, the PG pulse and _the signal VD ₁ have a predetermined phase relationship as shown in FIG.
It lags behind VD ₁ by τ ₁ hour. This τ ₁ takes a different value each time the magnetic sheet 1 is attached. A comparison output corresponding to this τ ₁ is obtained from the phase comparator 21,
The value is stored in memory 29.

On the other hand, a wobbling component is detected from the reproduction signal of the head 9 by a detection circuit 25, and this detection signal and the wobbling signal are compared by a phase comparator 27. As a result, a signal corresponding to the amount of eccentricity of the reference track 2 is obtained. This signal is stored in memory 29 and is applied to adder 15 via switch 30 and amplifier 31 to be superimposed on the drive voltage, thereby controlling head arm 10. Auto-tracking of the head 9 is thereby accomplished.

Next, when the reproduction of the reference track 2 is completed, the switches 19 and 30 are closed to the REC side, the switch 23 is closed to the REC ₂ side, and recording of the signal S _v is started. Along with this, the signal S ₁ from the memory 29,
_S3 is read. In this recording state, the signal S _v is sequentially recorded by the head 9 starting from, for example, the outermost track. At this time, a signal _S3 corresponding to the amount of eccentricity is read out from the memory 29. The head arm 10 is controlled by superimposing this signal _S3 on the drive voltage in the adder 15. As a result, the head 9 is controlled according to the eccentricity, and a recording track concentric with the reference track 2 is formed. Further, the signal VD ₁ of the signal S _v is applied to the delay circuit 22, and the delay time of this delay circuit 22 is controlled by the signal S ₁ corresponding to the above-mentioned τ ₁ read out from the memory 29. As a result, the signal VD ₁ is delayed by τ ₁ and substantially moved to the position of VD ₂ in FIG. 3, and phase servo is applied using this delayed signal VD ₁ as a reference.

That is, the delayed signal VD ₁ and the PG pulse are phase-compared to control the motor 3, and the delayed signal VD ₁ and the PG pulse are compared with the signal VD ₁ in FIG.
The servo is locked when the phase relationship is the same as that with the PG pulse. The signal S _v thus recorded is recorded in the same phase as the reference signal of the reference track 2, and therefore, regardless of the mounting position of the magnetic sheet 1, the vertical synchronization signal of the recording track is the same as the vertical synchronization signal of the reference track. It can be adjusted to the position of

According to the above, when recording, first the reference track 2 is reproduced, the phase difference and eccentricity between the signals VD ₁ and VD ₂ are detected and stored, and the signals stored during recording are read out. Since the head 9 and the servo reference are controlled, all recording tracks can be formed concentrically and with the vertical synchronization signals aligned. In addition, if you want to proceed to recording the signal S _v without removing the magnetic sheet 1 after recording the reference track 2, switch 19 is
Recording is performed on the REC side with the switch 23 closed to the REC ₁ side. In this case, each track is formed concentrically with the reference track 2, and the vertical synchronization signals are also aligned. Further, when reproducing the magnetic sheet 1 recorded as described above, the switches 19, 23, and 30 are closed to the PB side. Therefore,
Phase servo is performed using the signal VD ₂ of the reproduced signal as a reference, and the auto-tracking described above is also performed. Incidentally, since the phase of the horizontal synchronization signal obtained from the reproduced signal varies depending on the eccentricity, automatic tracking may be performed by detecting this.

Next, an embodiment in which various data are recorded on the reference track 2 will be described.

Signals having various contents are recorded on the magnetic sheet 1 used in this type of VSR. For example, (1) an audio track that is paired with a picture track.

(2) 1-field still images, (3) 1-frame still images, (4) endless videos, (5) unidirectional videos, and so on. Therefore, during reproduction, it is necessary to know what content is recorded on which track on the magnetic sheet. For example, educational VSR
etc., playback is performed in sequence according to the program. Therefore, in this embodiment, the reference track 2 includes the track number (address) of the magnetic sheet,
I try to record the table of contents, programs, and other necessary data. At the time of reproduction, first the reference track 2 is reproduced, and then the reproduction processing circuit 26 shown in FIG.
The output is applied to the data detection circuit 34 to extract data, and this data is stored in the memory 29. Next, when reproducing the recorded track, the drive power supply 14 is controlled by the signal _S2 having the contents of the above data read out from the memory 29, and the head 9 is controlled to move to the track of the number specified by the data. . In this case, a cueing address may be recorded on each track. Alternatively, a data track may be provided separately from the reference track, only the address of the data track may be recorded on the reference track, and necessary data may be read from the data track.

As described above, in the present invention, a reference signal including a vertical synchronization signal is recorded on a track in advance, and the reference track is first recorded while applying phase servo with reference to the vertical synchronization signal of a video signal applied from the outside during recording. The phase difference between the reproduced vertical synchronization signal and the vertical synchronization signal of the video signal is detected and stored, and then the vertical synchronization signal of the video signal is The synchronizing signal is delayed, and the video signal is recorded on the annular track while applying the phase servo using the delayed vertical synchronizing signal as a reference.

Therefore, according to the present invention, it is possible to perform recording by aligning the vertical synchronizing signals of all tracks without providing positioning holes or the like in the magnetic sheet and without causing deterioration of servo characteristics.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a magnetic sheet, FIG. 2 is a circuit diagram showing an embodiment of the present invention, and FIG. 3 is a timing chart showing the operation of the main parts of FIG. In addition, in the symbols used in the drawings, 1...Magnetic sheet, 2...Reference track, 5...PG, 7,2
1... Phase comparator, 8... Drive circuit, 20,
33... Vertical synchronization separation circuit, 22... Variable delay circuit, 23... Switch, 29... Memory.

Claims (1)

[Claims] 1. A reference signal including a vertical synchronization signal is recorded in advance on an annular reference track formed at a predetermined position of a recording medium, and when recording a video signal, the recording medium is rotated using the vertical synchronization signal of this video signal as a reference. The reference track is first reproduced while applying phase servo, the phase difference between the reproduced vertical synchronization signal and the vertical synchronization signal of the video signal is detected and stored in a storage device, and then read out from the storage device. A recording and reproducing method in which a vertical synchronizing signal of the video signal is delayed in accordance with the phase difference, and the video signal is recorded on a circular track while applying the rotational phase servo using the delayed vertical synchronizing signal as a reference. .