JPH0475582B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a tape recorded by a rotating head type helical scan type recording device, and furthermore, the recording speed can be adjusted by changing the number of rotations of the rotating head or the tape speed. The present invention relates to a method for automatically determining the recording speed when reproducing a tape that can be recorded by changing the recording track pitch by changing the recording speed.

BACKGROUND TECHNOLOGY AND PROBLEMS In popular household VTRs, when performing tracking control in which a rotating head correctly scans a recording track, conventionally a fixed magnetic head is used to generate control signals in the longitudinal direction of the tape. This is done using playback control signals from the track. However, this method of using a fixed magnetic head is disadvantageous because the width of the tape increases and the size of the recording/reproducing apparatus is desired to be reduced because of the location of the fixed head.

Therefore, a method of tracking control without using such a fixed head was proposed.

In this method, the track for recording the video signal is
A low-frequency pilot signal for tracking is recorded by a rotating head in superimposition with this, and during playback, the amount of crosstalk of this pilot signal from an adjacent track is detected to perform tracking servo. For this reason, the pilot signal is frequency-multiplexed so that it can be easily separated during playback as a low-frequency signal in the frequency spectrum where no video signal recording signal exists, and it is also recorded so that crosstalk cannot be removed much with azimuth loss. A low frequency is selected.

First, an overview of this tracking control method will be explained.

In this example, pilot signals of four different frequencies are cyclically and sequentially frequency-multiplexed recorded on diagonal tracks. For example, when recording is performed using a rotary head device in which two rotary heads HA and HB with different azimuth angles are arranged 180° apart, recording is performed in a so-called overwritten state as shown in Figure 1. When the tracks are sequentially formed, these two rotating heads record the video signal and sequentially transmit four pilot signals of four different frequencies ₁ , ₂ , ₃ , and _4, one each, as shown in Figure 1. It is changed for each track and recorded cyclically.

In other words, one of the rotating heads HA
As shown in the figure, every other track T ₁ and T ₃ are formed to record an FM modulated video signal, and track T ₁ receives a pilot signal of frequency ₁ , and track T ₃ receives a pilot signal of frequency ₃ . The pilot signals are respectively superimposed and recorded. In addition, every other track is moved by the other rotary head HB.
T ₂ and T ₄ are sequentially formed to record the FM modulated video signal, and track T ₂ has a frequency
₂ pilot signal, and track T ₄ has a frequency ₄ pilot signal.
The pilot signals are superimposed and recorded. By repeatedly recording these tracks _T1 to _T4 , pilot signals of four different frequencies are also sequentially recorded to these tracks T1 to _T4 .
It is recorded cyclically for T ₄ .

Tracking control during playback is performed as follows.

In this case, head HA is in the just tracking state when it correctly scans tracks T ₁ and T ₃ , and head HB is in the just tracking state when it correctly scans tracks T ₂ and T ₄ . . Therefore, assuming that the gap widths of heads HA and HB match the track width, when heads HA and HB sequentially scan tracks _T1 to _T4 , the reference pilot signal is synchronized with this. When the signals P ₁ to P ₄ of frequencies ₁ to ₄ are supplied to the multiplication circuit and the frequency difference with the reproduced pilot signal is detected, the frequency difference cannot be obtained in the just tracking state.

On the other hand, if the tracking position deviates as shown in (1) and (2) of the head position (this is the case of head HA) in Figure 1, the signal from the adjacent track may have a different frequency from the reference pilot signal. Since the pilot signal is obtained as crosstalk, a frequency difference occurs between the pilot signal and the crosstalk signal, and the level is proportional to the amount of difference.

Therefore, tracking servo can be easily performed by selecting frequencies ₁ to ₄ so that the above frequency difference is the same in the direction of deviation between tracks T ₁ and T ₃ and between T ₂ and T ₄ . . That is, Δf _A = |f ₁ −f ₂ |=|f ₃ −f ₄ | Δf _B = |f ₂ −f ₃ |=|f ₄ −f ₁ |. In this way, the existence of the frequency difference Δf _A means a shift to the right with respect to the head HA, a shift to the left with respect to the head HB, and the frequency difference Δf _B
The existence of the head HA is offset to the left, and the head
For HB, it means a right shift, and the levels of the differences Δf _A and Δf _B are proportional to the amount of shift.

Therefore, in principle, these frequency differences Δf _A and Δf _B
indicates the amount of tracking error, and if this is controlled to become zero, just tracking can be achieved.

However, since this example is a case of overwriting, as shown by the solid line 3 in Fig. 1, the state in which the track that is originally to be scanned spans the tracks on both sides by slightly the same amount is called just tracking. It is in a state of That is, just tracking occurs when the levels of the frequency differences Δf _A and Δf _B are equal, and tracking control is performed by controlling the level difference between the frequency differences Δf _A and Δf _B to be zero.

FIG. 2 is a block diagram of an example of the tracking control device.

This example is for an 8 mm video, where the pilot signal is a signal that is even lower than the low frequency conversion carrier chrominance signal band, and has four frequencies ₁ , ₂ , ₃ , _4.
For example, ₁ = 102kHz, ₂ ] 116kHz, ₃ = 160k
Hz, ₄ = 146kHz, Δf _A = 14kHz, Δf _B =
It is said to be 44kHz.

In Figure 2, the playback outputs of heads HA and HB are rotary transformers 11A and 11, respectively.
B is supplied to the switch circuit 13 through the head amplifiers 12A and 12B, respectively, and the head switching signal RFSW is sent through the terminal 14 (as shown in FIG. 3A, the switch circuit 13 synchronizes with the rotation of the heads HA and HB, The head HA or HB is switched to one terminal and the other terminal alternately during the 180° square interval when the tape is scanned.Therefore, the output of the amplifier 15 is the playback output of the heads HA and HB continuously. A connected signal is obtained,
This is supplied to the reproduction signal processing system through the terminal 16.

The output of the amplifier 15 is also supplied to a low pass filter 21 to extract a pilot signal from the reproduced signal. The reproduced pilot signal from this low-pass filter 21 is supplied to a multiplication circuit 22.

On the other hand, a pilot signal generation circuit 23 is provided, from which reference pilot signals P ₁ , P ₂ , P ₃ , and P ₄ of frequencies ₁ , ₂ , ₃ , and ₄ are obtained, and these are supplied to a switch circuit 24. . This switch circuit 24 receives a head switching signal from the terminal 14.
The switch is switched by the RFSW in synchronization with the head switching, and for example, during the 180° period when the head HA scans the track _T1 , the switch control circuit 24 outputs the signal _P1 of frequency ₁ as the reference pilot signal.
However, during the 180 period during which the head HB scans the track _T2 , the signal _P2 of frequency ₁ is obtained by sequentially switching four frequency signals _P1 to _P4 (Fig. 3). B).

The reference pilot signal from the switch circuit 24 is supplied to the multiplication circuit 22. Therefore,
From this multiplication circuit 22, signals with frequencies Δf _A and Δf _B , which are the difference between the reference pilot signal and the reproduced pilot signal, are obtained, and these are taken out by band pass filters 25 and 26, respectively, and detected by detection circuits 27 and 28, respectively. The waves are detected and output as DC level outputs SA and SB. These detection outputs SA and
SB is the amount of components at frequencies Δf _A and Δf _B , respectively;
That is, the level is proportional to the magnitude of the pilot signal included as crosstalk in the reproduced pilot signal, and corresponds to the amount of tracking of the adjacent tracks on the right and left.

These detection outputs SA and SB are supplied to a subtraction circuit 29, and a subtraction output SD of both is obtained from this. This subtraction output SD is a signal that indicates which side is more deviated from the left or right side, but as mentioned above, the frequency difference Δf _A and Δf _B between the scanning of the head HA and the scanning of the head HB are as follows. The direction of the shift is reversed.

Therefore, the output SD of the subtraction circuit 29 is supplied as is to one input terminal of the switch circuit 30, and the polarity is inverted via the polarity inverting circuit 31 and supplied to the other terminal of the switch circuit 30. and,
This switch circuit 30 is a head switching signal.
When scanning head HA and head HB by RFSW
By switching alternately during scanning, the amplifier 32 obtains a tracking error voltage SE corresponding to the shift direction. Therefore, if this is supplied by a capstan motor, tracking control will be applied.

For example, when the head HA is in a scanning state shifted to the right as shown at position 2 in FIG. It also includes the pilot signal of the truck on the right. Then, as shown in FIG. 3D, the multiplier circuit 22 alternately obtains frequency differences Δf _A and Δf _B that are shifted to the right for the heads HA and HB in each scanning period. Therefore, the output SA of the detection circuit 27 becomes as shown in FIG. E, the output SB of the detection circuit 28 becomes as shown in FIG. F, and the subtracted output SD becomes as shown in FIG. Then, the tracking error signal SE enters a state indicating a right-shift error as shown in H in the figure.

As described above, tracking control during reproduction can be performed without using a fixed magnetic head.

By the way, in the case of this type of recording/reproducing apparatus, recording is generally performed by changing the tape speed and recording track pitch depending on the purpose. That is, for example, when the tape speed is increased, the recording time becomes relatively short, but since the track pitch is wide, crosstalk from adjacent tracks can be reduced. This is hereinafter referred to as short play mode (hereinafter referred to as SP mode). On the other hand, when the tape speed is slowed down, the recording time becomes longer, but the track pitch becomes narrower, so crosstalk from adjacent tracks becomes large, and removal of this influence becomes a problem. This is hereinafter referred to as long play mode (hereinafter referred to as LP mode).

For example, when the recording track pattern shown in FIG. 1 is in LP mode, if the tape speed is doubled, the recording track pattern becomes SP mode as shown in FIG. A guard band is formed between the two, and crosstalk is reduced.

Note that even when the magnetic head is not scanning directly above a track, signals from adjacent tracks are mixed into the head output, and since the frequency of the pilot signal for tracking is low, even in this SP mode, the above-mentioned 4 Tracking servo using pilot signals of two frequencies can be performed.

When playing back a tape that can be recorded in SP mode and LP mode as described above, if the tape speed is different during recording and playback, that is, when playing back in different modes, the rotating head will not work properly. Since the recording track cannot be scanned, reproduction becomes impossible. Therefore, when playing back a recorded tape, it is necessary to determine whether it was recorded in SP mode or LP mode, and it is useful for users to be able to do this automatically. That's preferable.

In conventional popular VTRs, as described above, a control signal from a fixed head is used for tracking control, and this control signal is recorded at a recording pitch corresponding to the recording track pitch. If the tape speed is the same during recording and playback, the playback frequency of this control signal is played back as a signal with a constant cycle. Conventionally, the recording speed was automatically determined by detecting the cycle of this playback control signal. was being carried out.

However, in a device that performs tracking control without using a fixed head as described above, this discrimination method using a fixed head cannot be performed, so some other discrimination method is required.

Note that even if the number of revolutions of the rotary head is changed without changing the tape speed, a recording pattern in which the recording track pitch changes as shown in FIGS. 1 and 4 will result, and this also needs to be determined.

Purpose of the Invention As described above, the present invention uses a tracking control method in which pilot signals of a plurality of frequencies are frequency-multiplexed recorded on an information signal without using a fixed head, and the reproduced pilot signal output is used during reproduction. , when there are multiple recording speeds,
The aim is to provide a method for automatically determining this during playback.

SUMMARY OF THE INVENTION This invention provides a method for changing the track pitch by changing the recording speed (it is possible to change either the number of rotations of the rotary head or the tape speed). This method takes advantage of the fact that when the signal is doubled, the track pitch doubles as shown in Figure 4.The reproduction pilot signal is extracted by the erasing rotary head, which has a wider gap than the reproduction rotary head, and this Since the scanning width of the erasing rotary head relative to the recording track changes when the recording speed is changed, the signal frequency component extracted as the reproduction pilot signal differs, and this is detected to determine the recording speed. be.

Embodiment In the case of a rotary head type helical scan type recording and reproducing apparatus, a rotary head for erasing is provided in consideration of continuous recording and editing. This erasing rotary head has a gap wider than that of the recording/recording/reproducing rotary head in order to complete erasing.

The present invention uses this rotary erasing head.

FIG. 5 shows an example of a rotary head device used in the apparatus of the present invention. In addition to two recording/reproducing rotary heads HA and HB with different azimuths arranged 180 degrees apart, in this example, there are two rotary heads HA and HB for recording and reproducing with different azimuths. An erasing rotary head FE is provided at a position preceding the rotation angle by .degree. rotation angle. And rotary heads HA and HB for recording and reproduction.
In the LP mode, recording is performed by forming a recording track pattern as shown in FIG. 1, and in the SP mode, recording is performed by forming a recording track pattern as shown in FIG. 4.

As shown in Fig. 5, the erasing rotary head FE has a gap g _E that is wider than the gaps g _A and g _B of the heads HA and HB, and in this example, the gap width is twice the track pitch in SP mode. have. During recording, prior to signal recording by the heads HA and HB, erasing is performed by the erasing head FE over an area of two tracks or more, which is the scanning position of these heads HA and HB. .

Therefore, as shown in FIG. 1, for the recording tracks of a recorded tape in LP mode, this erasing head FE has four tracks T ₁ , T ₂ , T ₃ ,
The erasing head scans over exactly ₄ minutes, and as shown in Figure 4, for the recorded tracks of a recorded tape in SP mode, this erasing head scans over two tracks. becomes. Therefore, during reproduction, by detecting the difference in frequency components of the reproduction pilot signal from the erasing head FE, it is possible to determine the difference in recording speed (hereinafter referred to as mode determination). Detection of the difference in frequency components contained in this reproduced pilot signal can be performed using a circuit for detecting frequencies Δf _A and Δf _B of a tracking control circuit, as will be described later.

FIG. 7 is a system diagram of an example of a reproducing apparatus to which the method of the present invention is applied, and parts corresponding to those in the example of FIG. 2 are designated by the same reference numerals.

In this example, the recording/reproducing rotary head HA
and a rotary head for tracking control and erasing using the reproduction pilot signal obtained from the reproduction output of the HB.
Mode discrimination using a reproduced pilot signal obtained from the reproduced output of the FE is performed in a time-sharing manner.

40 is a switch circuit for this purpose. That is, the reproduced outputs of the heads HA and HB from the amplifier 15 are supplied to one input terminal of the switch circuit 40.

Further, the output obtained during the track scanning period of the erasing rotary head FE is supplied to the other input terminal of this switch circuit 40 through a rotary transformer 41 and an amplifier 42.

Here, when the head output switching signal RFSW has a phase as shown in FIG. 8A, and when the head HA scans the recording track during its high level period and the head HB scans the recording track during its low level period, the head HA's phase changes. The output has a phase as shown in the figure B, and the output of the head HB has a phase as shown in the figure C. And the head FE is the head
Since the phase is 90° ahead of HA, its output timing is as shown in FIG.

The mode determination is made during the period when the reproduction output is obtained from the erasing rotary head FE, but the head
It is not necessary to use the entire FE track scanning period (180° rotation); any period long enough for discrimination is sufficient. Therefore, in this example, the switch circuit 40 is switched by the switching signal SW (Fig. 8E), but when the head FE scans the recording track, the period corresponding to the 180° rotation is This signal also occurs in the PM for a short period of time.
When SW becomes high level, the switch circuit is switched to the other input terminal side to obtain the output of the erasing head FE as the output, and during other periods PS is switched to the state shown in the figure to select the output of the amplifier 15. be done.

The switching signal SW is generated in a control signal generation circuit 50, which in this example consists of a microcomputer. This generating circuit 50 includes a rotating head.
A signal indicating the rotational phase of HA and HB is supplied, and a signal for selecting the reference pilot signal is also supplied.
SL ₁ and SL ₂ are also formed.

From the above, the period PS is considered to be a tracking control period, and the switch circuit 40 outputs a head signal.
Reproduction outputs of HA and HB are obtained, which are supplied to a low-pass filter 21 to extract a reproduction pilot signal. During this period PS, the reference pilot signal selection signals SL ₁ and SL ₂ supplied from the control signal generation circuit 50 to the switch circuit 24 are synchronized with the signal RFSW as shown in FIG. As shown, each head HA
and frequency ₁ , ₂ ,
It is assumed that reference pilot signals ₃ and ₄ are selected in sequence. Therefore, during this period PS, tracking control as described above is performed using the reproduction pilot signals obtained from the outputs of the rotary reproduction heads HA and HB. However, in this example, tracking control is performed only during the period PS, so the signal from the subtraction circuit 29 is sampled and held in the sampling hold circuit 51 only during the period PS, and its output is supplied to the switch circuit 30 and the inverter 31. be done.

On the other hand, during the mode discrimination period PM, the selection signal SL ₁
and SL ₂ , the switch circuit 24 is constructed as shown in FIG.
As shown, reference pilot signals of four types of frequencies ₁ , ₂ , ₃ , and ₄ are selected for each period of PM/4 within this period PM.

The output SD of the subtraction circuit 29 is then supplied to the mode discrimination circuit 52. This mode discrimination circuit 52 is also supplied with a signal from the control signal generation circuit 50, so that this discrimination circuit 52 is kept in an operating state only during the mode discrimination period PM.

For a tape recorded in the LP mode, the erasing rotary head FE scans over exactly four tracks _T1 to _T4 as shown in FIG.
Even if the tracking phase is shifted as shown in the figure, for the four tracks T ₁ , T ₂ , T ₃ , and T ₄ , it is equivalent to scanning exactly one track each, so the reproduction output is The pilot signal inside contains the same amount of components of frequencies ₁ to ₄ .

Therefore, in this LP mode, the reproduced pilot signal output from the low-pass filter 21 is as shown in FIG. 10A. Therefore, when signals with frequencies ₁ to ₄ are sequentially supplied as reference pilot signals for each PM/4 period in period PM as shown in figure B, the detection outputs SA and SB will be as shown in figure C and D.
As shown in Figure E, the signals are at the same level during this period PM, and the output SD of the subtraction circuit 29 becomes zero as shown in Figure E.

On the other hand, a tape recorded in the SP mode is scanned over two or three tracks as shown in FIG. Then, during the period PM, when reference pilot signals of four different frequencies are supplied to the multiplication circuit 22, for each scanning position a to h of the head FE in FIG. signal with a waveform
SD is obtained from the subtraction circuit 29, respectively. For example, at the scanning position a of the head FE in FIG. 11, it scans across tracks T ₃ and T ₄ , but at this time, for the reference pilot signal of frequency ₁ , Δf _B =
The difference component of | ₁ − ₄ | is obtained, and for the reference pilot signal of frequency ₂ , Δf _B = | ₂ − ₃ |,
For the reference pilot signals of frequencies ₃ and ₄ , Δf _A = | ₃ − ₄ | is obtained, respectively, and the subtraction circuit 2
The signal SD from 9 becomes as shown by a in FIG.

That is, in the SP mode, as shown in FIG. 12, a signal of a certain level or higher, which is the same as when a tracking error occurs, is obtained as the output SD. As mentioned above, in the LP mode, the output SD is a signal with a zero level, so the mode discrimination circuit 52 determines whether the output SD is above a certain level or not to determine whether it is the LP mode or the SP mode.
mode can be determined.

The mode discrimination output thus obtained is supplied to the control signal generation circuit 50. Although not shown, a mode switching signal is obtained from the control signal generation circuit 50 according to this mode determination,
This allows, for example, the speed of a capstan motor to
Therefore, the tape speed is controlled to be the same as the recording mode.

However, in order to avoid errors and false detections as much as possible in this mode discrimination, a microcomputer is used as the mode discrimination circuit 52 in this example, and the process is as follows. First, the output SD is converted into a digital signal and supplied to the mode discrimination circuit 52, and the select signals SL ₁ and SL ₂ are supplied as timing control signals. And the output
The difference between the maximum and minimum SD values is detected, and if the detection output is greater than a certain value, the SP mode is activated.
If it is smaller, it is determined to be LP mode, but in order to avoid errors, the mode is determined when the same result is obtained several times in a row. A flowchart for this purpose is shown in FIG. Here, N and M are integers greater than or equal to 2, and N=M
However, N≠M is also acceptable. In other words, if the difference between the maximum value and the minimum value of the output SD is equal to or greater than a certain value for N or more consecutive times, it is determined to be SP mode, and if the difference is not equal to or greater than a fixed value for M or more consecutive times, it is determined to be LP mode. , respectively, if the number of times is N or less, and if it is less than or equal to M, the previous mode is maintained.

In the above example, the circuit system that forms the error signal for tracking control is also used when creating the mode discrimination signal, so mode discrimination and tracking control are performed in a time-sharing manner. There is no need to do this if a circuit system is provided.

Also, the gap width of the rotating head FE for erasing is
An example in which the track pitch in SP mode is doubled has been described, but the gap width of head FE only needs to be wider than that of heads HA and HB. The point is that if the scanning width for the recording track is different between the SP mode and the LP mode, the frequency components included in the reproduction pilot signal will be different, and this is used to determine the mode.

FIG. 14 shows another example of the present invention, in which rotary erasing heads FE _A and FE _B are provided at positions 90° ahead of heads HA and _HB , respectively. The gap width of FE _B is
It is said to be 1.5 times the track pitch of SP mode.

In this case, for SP mode recording tape, heads RE _A and FE _B are set as shown in Figure 15.
Scans 1.5 tracks. On the other hand, for an LP mode recording tape, heads FE _A and FE _B scan three tracks as shown in FIG.

Therefore, the head switching signal RFSW is
If the head is as shown in Figure A and the pilot signals obtained from the playback outputs of heads HA and HB are as shown in Figures B and C, then the head FE _A
The pilot signal obtained from the reproduction outputs of FE _B and FE B causes the heads FE _A and FE _B to scan the track scanned by the heads HA and HB and the adjacent track by 1/2, as shown in Fig. D. and E
It will look like the one shown below.

On the other hand, if an LP mode recording tape is to be played back, the heads FE _A and FE _B scan across three tracks, so the pilot signals obtained from the playback output are as shown in Fig. 18D and FE B. It will look like E.

In this example, mode discrimination is performed using a dedicated circuit system, and the reference pilot signal for the reproduction pilot signals of heads FE _A and FE _B is
One tape scanning period each for FE _A and FE _B
In the PA, four signals with frequencies Δ ₁ to ₄ are switched sequentially every 1/4 PA period, and the switching order is as shown in Figures 17F and 18F, starting from the first signal for each period PA. The frequencies are also changed sequentially.

In this way, in SP mode, the difference component Δf _A detection output SA becomes as shown in Figure 17H, and the difference component Δf _B
The detection output SB is as shown in figure G. Therefore, the subtracted output SD becomes as shown in the same figure, and has a waveform that changes in two steps as a positive or negative level.

On the other hand, in LP mode, the detection output SA of the difference component Δf _A
is as shown in Figure 18H, and the difference component Δf _B detection output
SB will look like G in the same figure. Therefore, the subtraction power SD
As shown in the figure, the signal has a waveform that takes only one level, either positive or negative.

Therefore, in the mode discrimination circuit 52 having a microcomputer, the subtraction output is performed while timing is controlled by the select signals SL ₁ and SL ₂ .
SP mode and LP by monitoring the waveform of SD
It becomes possible to distinguish between modes.

In the above example, the tracking servo uses the reproduced pilot signal obtained from the reproduced output of heads HA and HB in both SP mode and LP mode, but in SP mode, a guard band is formed between tracks. In heads HA and HB, crosstalk from adjacent tracks becomes small, and tracking control may not be stable. Therefore, in the SP mode, the reproduction pilot signal from the reproduction output of the erasing rotary head FE, which has a wider gap width than the heads HA and HB, may also be used for tracking control. In this case, if the circuit from the low-pass filter 21 to the subtraction circuit 29 is shared, mode discrimination and tracking control are performed in a time-sharing manner, and the mode discrimination circuit 5
2, the frequencies of the reference pilot signals selected by the select signals SL ₁ and SL ₂ are ₂ and 2.
₄ , the polarity of the subtraction output SD is inverted so that a tracking error signal can be obtained from the mode discrimination circuit 52. Even if this is done, there is no effect on waveform discrimination for mode discrimination. Then, the mode discrimination circuit 5
2 output and amplifier 32 output in SP mode and LP mode.
The mode may be switched during the tracking control period PS. Of course, if mode discrimination and tracking control are performed in separate systems, the input signal to the tracking control system can be switched between the output of the head FE and the output of the heads HA and HB between SP mode and LP mode. Just do it like this.

The same applies to the example shown in FIG.

Effects of the Invention According to the present invention, by utilizing the fact that the erasing rotary head generally has a wider gap width than the recording/reproducing rotary head, the piste signal component from the output of the erasing rotary head is extracted and included therein. By detecting differences in frequency components, differences in recording speed can be determined during reproduction.

[Brief explanation of the drawing]

FIG. 1 is a recording track pattern diagram for explaining a tracking control method that does not use a fixed head, FIG. 2 is a system diagram of an example of the tracking control system, FIG. 3 is a time chart for explaining the same, and FIG. The figure shows an example of a recording track pattern when the recording speed is changed, FIGS. 5 and 6 show an example of a rotary head device used in an example of the method of this invention, and FIG. 7 shows an example of a rotary head device for realizing the method of this invention. A system diagram of an example of the device, FIGS. 8 to 13 are diagrams for explaining the same, FIG. 14 is a diagram showing an example of a rotary head device used in another example of the method of this invention, and FIGS. 15 to 1
FIG. 8 is a diagram for explaining the same. HA, HB are rotary heads for recording and playback, FE, FE _A
and FE _B are rotary heads for erasing, 21 is a low-pass filter for extracting the reproduced pilot signal, 22 is a multiplication circuit for detecting the frequency difference between the reference pilot signal and the reproduced pilot signal, and 27 and 28 are frequency differences Δf _A and Δf. This is a level detection circuit for _{the B} component.

Claims (1)

[Claims] 1. A recording medium in which an information signal is recorded as a diagonal track by a rotating head, and a plurality of pilot signals with different frequencies are cyclically frequency-multiplexed with the information signal on the diagonal track, wherein the track pitch is During playback of a disc capable of recording at first and second recording speeds with different speeds, the playback signal of the pilot signal is extracted from the output of the erasing rotary head, which has a wider scanning width than the playback rotary head, and the recording track is The recording speed is determined by detecting a difference in the frequency component of the reproduced signal of the pilot signal due to a difference in the scanning width of the erasing rotary head between the first recording speed and the second recording speed. Automatic speed determination method during playback.