JPH0817004B2 - Recording device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording device for recording a video signal or an audio signal by using a rotary head, and in particular, a so-called joint recording for connecting to a recorded portion for recording. Involved in Rino's technology.

[Conventional technology]

In a VTR, a "joint recording" method is generally used in which a joint is made inconspicuous on a playback screen when recording is performed by connecting to a recorded portion.

As shown in FIG. 5, when the recording pause is turned on from the reproduction state or the recording state to perform the joint recording, the tape is returned from the position P ₁ of the pause switch on by a predetermined amount, and then in the middle of the recorded portion. Pause at a certain position P ₂ . And if you release the pose from this state,
During the period from this position P ₂ to the position P ₃ corresponding to the tape position P ₁ when the pause switch is turned on (corresponding to the tape return amount), the device is in the reproduction mode and the reproduction tracking servo that uses the reproduction output of the recorded part It takes. Then, when the position P ₃ is reached while the reproduction tracking servo is applied, the apparatus enters the recording mode and the continuous recording is performed.

In this case, the tracking servo is applied in front of the joint, and the rotary head is in a state of correctly scanning the recorded track, and the scanning state of this rotary head continues even after entering the recording mode. The continuity of the tracks is maintained before and after, and a smooth image with no noticeable noise is displayed on the playback screen.

By the way, in a video signal recording apparatus, in order to increase the recording density, two rotary heads having different azimuths are used, and the gap width of these heads is made larger than the track width to form a guard band between adjacent tracks. It is generally practiced to sequentially form and record tracks in a so-called overwritten state without doing so. Further, the reproducing tracking servo method described above uses only the rotary head without using the conventional fixed magnetic head, and particularly in the case of the so-called azimuth recording method as described above, the head scans across the adjacent tracks. ,
A method utilizing the fact that the signals of adjacent tracks can be easily obtained is adopted in, for example, an 8 mm VTR.

This tracking control method is disclosed, for example, in JP-A-59-659.
As described in Japanese Patent Laid-Open No. 62-62, on a track for recording a video signal, a pilot signal for low frequency tracking is recorded by a rotary head in superposition with this, and at the time of reproduction,
Tracking servo is performed by detecting the crosstalk amount of the pilot signal from the adjacent track. Therefore, the pilot signal is a signal on the low frequency side where the recorded signal of the video signal does not exist in the frequency spectrum,
Frequency multiplex recording is performed to facilitate separation during reproduction, and a low frequency is selected so that crosstalk cannot be removed by azimuth loss.

The outline of this tracking control method will be described first.

In this example, pilot signals of four different frequencies are cyclically frequency-multiplexed and recorded on diagonal tracks in a cyclic manner. For example, when two rotary heads HA and HB having different so-called azimuth angles are used for recording by a rotary head device which is arranged 180 ° apart, a recording track in a so-called overwriting state as shown in FIG. When these two rotary heads are sequentially formed, four pilot signals of four different frequencies f ₁ , f ₂ , f ₃ , f ₄ are sequentially recorded by these two rotary heads as shown in FIG. It is changed for each track of each book and recorded cyclically.

That is, as shown in FIG. 6, one rotary head HA forms every other track T ₁ , T ₃ to record the FM-modulated video signal, and the track T ₁ has the frequency f ₁ of the frequency f ₁ . The pilot signal and the pilot signal of the frequency f ₃ are recorded on the track T ₃ in a superimposed manner. In addition, by the other rotary head HB, every other track T ₂ , T
₄ are sequentially formed and the FM-modulated video signal is recorded and the pilot signal of frequency f ₂ is recorded on the track T ₂ .
Pilot signals of frequency f ₄ are recorded on track T ₄ in a superimposed manner. And this track
By repeatedly recording T _{1 to} T ₄ , pilot signals of four types of frequencies are also cyclically recorded on these tracks T _{1 to} T ₄ .

Tracking control during reproduction is performed as follows.

In this case, the head HA is in the state of just tracking when the tracks T ₁ and T ₃ are correctly scanned.
The HB is in the just tracking state when the tracks T ₂ and T ₄ are correctly scanned. Therefore, head HA and
Assuming that the gap width of HB matches the track width, when the heads HA and HB sequentially scan tracks T _{1 to} T ₄ , the frequency is used as a reference pilot signal in synchronization with this.
provides signals P ₁ to P ₄ of the f ₁ ~f ₄ in multiplication circuit detects a frequency difference between the reproduced pilot signal, no frequency difference is obtained in a just tracking state.

On the other hand, as shown in (1) and (2) of the head position (this is the case of the head HA) in FIG. 6, if the tracking position is deviated, a frequency different from the reference pilot signal from the adjacent track is detected. Since the pilot signal is obtained as crosstalk, a frequency difference is generated between the pilot signal and the crosstalk signal, and the level difference is proportional to the amount of deviation.

Therefore, the tracking servo can be easily performed by selecting the frequencies f _{1 to} f ₄ so that the frequency difference becomes the same in the direction of deviation between the tracks T ₁ and T ₃ and T ₂ and T _4. Become. 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 presence of the frequency difference Δf _A means right shift with respect to the head HA and the left shift with respect to the head HB, and the presence of the frequency difference Δf _B causes left shift with respect to the head HA, and head HB. To mean the right shift, respectively,
The levels of the differences Δf _A and Δf _B are proportional to the shift amount.

Therefore, in principle, these frequency differences Δf _A and Δf _B indicate the tracking error amount, and if it is controlled so that this becomes zero, just tracking can be performed.

However, in this example, since overwriting is performed, as shown by the solid line (3) in FIG. 6, the state in which just the same amount of scanning is performed over the tracks adjacent to the track to be originally scanned is just tracking. It is in a state. That is, just tracking is performed 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 differences Δf _A and Δf _B to be zero.

FIG. 7 is a block diagram of an example of the tracking control device.

In this example, for example, in the case of 8 mm video, the pilot signal is a signal lower than the band of the low-frequency conversion carrier color signal, and the four frequencies f ₁ , f ₂ , f ₃ , f ₄ are, for example, f ₁ = 102
kHz, f ₂ = 116kHz, f ₃ = 160kHz, f ₄ = 146kHz, Δ
It is assumed that f _A = 14kHz and Δf _B = 44kHz.

In FIG. 7, the reproduction outputs of the heads HA and HB are switched circuits (13) via rotary transformers (11A) and (11B) and head amplifiers (12A) and (12B), respectively.
Head switching signal RF through the terminal (14)
This switch circuit (13) is synchronized with the rotation of the heads HA, HB by the SW (Fig. 8A), and the head HA or HB scans the tape on the tape at 180 ° angular intervals for one and the other terminals, respectively. Can be switched to. Therefore, as the output of the amplifier (15), a signal in which the reproduction outputs of the head HA and HB are continuously connected is obtained, and this is the terminal (1
It is supplied to the reproduction signal processing system through 6).

The output of the amplifier (15) also has a low-pass filter (2
It is supplied to 1) and the pilot signal is extracted from the reproduced signal. The reproduction pilot signal from the low pass filter (21) is supplied to the multiplication circuit (22).

On the other hand, a pilot signal generation circuit (23) is provided, and a pilot signal P ₁ , which is a reference for frequencies f ₁ , f ₂ , f ₃ , and f ₄ is provided.
P ₂ , R ₃ and P ₄ are obtained and these are supplied to the switch circuit (24). The switch circuit (24) is switched in synchronization with the head switching by the head switching signal RFSW from the terminal (14), and, for example, the head HA scans the track T ₁ .
During the 180 ° period, the switch control circuit (24) outputs the signal P ₁ of frequency f ₁ as the reference pilot signal to the head.
In the 180 ° period in which the HB scans the track T ₂ , the signal P ₂ of the frequency f ₁ is obtained by sequentially switching the signals P _{1 to} P _{4 of the four} frequencies as shown in the following. (Fig. 8B).

The reference pilot signal from the switch circuit (24) is supplied to a multiplication circuit (22). Therefore, the signals of the frequencies Δf _A and Δf _B of the difference between the reference pilot signal and the reproduced pilot signal are obtained from this multiplication circuit (22), and these are extracted by the bandpass filters (25) and (26), respectively. The signals are detected by the detection circuits (27) and (28), and are output as DC level outputs SA and SB. These detection outputs SA and SB have levels that are proportional to the amounts of the components of the frequency differences Δf _A and Δf _B , respectively, that is, the magnitude of the pilot signal included as crosstalk in the reproduced pilot signal. It corresponds to the tracking amount.

These detection outputs SA and SB are supplied to a subtraction circuit (29), from which a subtraction output SD of both is obtained. This subtraction output SD is a signal indicating which one of the left side and the right side is deviated more. As described above, the frequency difference Δf _A and Δf _B are different between the scanning time of the head HA and the scanning time of the head HB. The direction of deviation is reversed.

Therefore, the output SD of the subtraction circuit (29) is directly supplied to one input end of the switch circuit (30) and also polarity-inverted via the polarity inversion circuit (31) to be supplied to the other terminal of the switch circuit (30). To be done. The switch circuit (30) is alternately switched by the head switching signal RFSW during scanning of the head HA and during scanning of the head HB, so that the tracking error voltage depending on the direction of deviation from the amplifier (32). SE is obtained. Therefore, if this is supplied to the capstan motor, tracking control is performed.

For example, when the head HA is in a state of scanning while being displaced to the right as shown at position (2) in FIG. 6, the reproduction pilot signal from the low pass filter (21) is as shown in FIG. 8C. In FIG. 6, the pilot signal of the adjacent track on the right side is also included. Then, from the multiplying circuit (22), as shown in FIG. 8D, frequency differences Δf _A and Δf _B indicating a right shift for the heads HA and HB are alternately obtained for each scanning period. Therefore, the output SA of the detection circuit (27) is
Then, the output SB of the detection circuit (28) becomes as shown in F in the same figure, and the subtraction output SD becomes as shown in G in the same figure. Then, the tracking error signal SE is in a state indicating an error of right shift as shown in FIG.

In the case of FIG. 7, the order in which the reference pilot signal from the switch circuit (24) is cyclically switched is the frequency f ₁ →
Since f ₂ → f ₃ → f ₄ → f ₁ → ..., the inverter (31)
Although a switch circuit (30) is provided, the order in which the reference pilot signals are cyclically switched in consideration of the direction of head deviation and the polarity of the output SD of the difference is f ₁ → f ₄ → f ₃ → f ₂ → f ₁ → ...
In this way, if the reference pilot signals of the frequencies f ₄ and f ₂ are exchanged, the inverter (31) and the switch circuit (30) need not be provided (see Japanese Patent Laid-Open No. 59-65962).

[Problems to be solved by the invention]

The recording format of overwriting for high-density recording described above is
As shown in FIG. 9, two rotary heads H having different head gaps g _A and g _B with different inclination angles, that is, different azimuths.
A and HB erase one copy of the track formed by the opponent's head alternately in sequence as shown in the figure, and record a new signal there to record tracks of constant width T ₁ , T ₂ , T ₃ , T ₄ , T ₁ , T _2, ... Are sequentially formed.

However, at the time of joint recording as described above, the scanning position (just tracking position) of the heads HA and HB during playback tracking servo at the tape return amount part.
As described above, is a position where the adjacent tracks on both sides of the track are scanned by the same amount, as described above. Therefore, at the next scan of the track T ₄ on the upper side of FIG. 10 where the reproduction mode is changed to the recording mode, a part of the track T ₄ indicated by hatching in FIG. 10 is overwritten and erased by the head HA. As a result, the recording track pattern on the tape after the joint recording is as shown in FIG. 11, and the track width of the last track T ₄ of the joint is narrowed.

When the track width is narrowed in this way, crosstalk from adjacent tracks increases during reproduction, and S / N deteriorates. Further, since it becomes the same as the tracking deviation, there is a possibility that jitter in the vertical cycle may occur and synchronization disorder may occur.

9 to 11, (4) shows the tape transfer direction, (5) shows the head scanning direction, and (T
₁ ), (T ₂ ), (T ₃ ), (T ₄ ) ... Denote newly recorded tracks.

[Means for solving problems]

According to the present invention, at the time of joint recording, when the reproduction tracking servo is performed by running the tape which has been released from the joint position and previously returned from the joint position, the reference pilot signal is obtained to obtain the frequency difference from the reproduction pilot signal. Different from the normal playback, the tracking position is shifted in the fast tape direction so that the end of the recording track on the tape transfer direction side and the end of the rotary head in the gap width direction match. To do.

[Action]

As described above, at the time of continuous recording, the heads HA and HB have their ends in the width direction of the tracks T ₁ and T as shown in FIG. 1 by the reproduction tracking servo before shifting to the recording state. Scanning is performed so as to coincide with the end of the tape in the tape transfer direction (4) side in the width direction of ₂ , T ₃ , T ₄ , and as a result, as shown in FIG. 2, the last track of the recording portion of the seam. The track width of T ₄ will not be narrowed.

〔Example〕

FIG. 3 is a block diagram of an embodiment of the present invention, in which the order of reference pilot signals is controlled so that the switch circuit (30) and the inverter (31) of FIG. 7 can be omitted. is there.

In this example, a switch control circuit (40) for switching a reference pilot signal and supplying a switching signal to a switch circuit (24) for supplying the multiplication circuit (22).
Is provided, and the head switching signal RFSW from the terminal (14) is supplied to the switch control circuit (40). In addition, a signal obtained when the pause switch is operated from the terminal (42) is supplied to the pause signal generation circuit (41), and when the pause signal generation circuit (41) is turned on, for example, the pause signal rises to a high level to release the pause signal. At that time, a pause signal PO that falls to a low level is obtained, and this is supplied to the switch control circuit (40). Others are configured similarly to the example of FIG.

From the switch control circuit (40), switch circuit (24)
Which of the four frequencies f ₁ , f ₂ , f ₃ and f ₄ are to be obtained from the switch control signals SL ₁ and SL ₂ (signal SL
₁ and SL ₂ form a 2-bit signal).

In the normal reproduction state, the control signals SL ₁ and SL ₂ from the switch control circuit (40) are the head switching signal RF.
It is changed in synchronization with SW (Fig. 4A). From the switch circuit (24), as shown in Fig. 4B, f ₁ → f ₄ → f ₃
Four kinds of reference pilot signals that are repeated in the order of → f ₂ → f ₁ are obtained, and tracking servo is applied in the same manner as described above so that the head scanning device (3) in FIG. 6 is obtained.

Next, from position P _{2 in} FIG.
The reproduction tracking servo up to P ₃ will be described.

First, when the joint is found in the normal reproduction state, the pause switch is pressed and the record button is pressed, and the record pause is turned on, the output signal PO of the pause signal generation circuit (41) rises, and at the time of the rise, Signals SL ₁ and S at that time of the switch control circuit (40)
The state of L ₂ is stored.

Next, when the pause is released, the pause signal generation circuit (41)
Output signal PO of the switch falls, and from that point of time, the control signals SL ₁ and SL ₂ from the switch control circuit (40) are the signals.
It changes not only at the fall and rise times of RFSW, but also at the time when a period a has elapsed from the fall and rise times. In this case, the length of the period a is C, which is a half cycle of the signal RFSW, and the heads HA and HB are located at the ends of the tracks T ₁ , T ₂ , T ₃ , T ₄ , as shown in FIG. When the total width of the head HA is g ₁ when the head is scanned and g ₂ is the width of the gap portion extending over the adjacent track, it is determined that c: a = g ₁ : g ₂ .

Then, from the switch circuit (24), as shown in FIG. 4C, the normal reproduction shown in FIG. 4B is performed during the remaining period b excluding the high level period a and the low level period a of the signal RFSW. A reference pilot signal similar to that at the time is obtained, and in the period a, in the reference pilot signal at the time of normal reproduction shown in FIG. 4B, the high level period including the period a and the high level next to the low level period are included. And a reference pilot signal obtained in the low level period.

By switching the reference pilot signal in this manner, reproduction tracking servo is applied so that the heads HA and HB are brought into the scanning state shown in FIG.

That is, in FIG. 1, when the head HA mainly scans the track T ₁ in the reproduction mode as shown in FIG.
The reproduction pilot signal output from this head HA has a frequency f ₁
And the component of f ₂ is obtained, but the level of the component of frequency f ₁ is set to 1
, The level of the component of frequency f ₂ is g ₂ / (g ₁ −g ₂ ).
Is.

To the reproduction pilot signal output, the reference pilot signal having the frequency f ₄ in the period a and the frequency f _{1 in} the period b is supplied to the multiplication circuit (22) from the switch circuit (24). The difference Δf _B between the reference pilot signal of frequency f ₄ and the reproduced pilot signal of frequency f ₁ in period a
Is obtained at the level La, and the difference Δf _{A from} the reproduced pilot signal of the frequency f ₂ is obtained at the level Lb for the reference pilot signal of the frequency f ₁ in the period b. Therefore the amplifier (32)
A signal as shown in FIG. 4D is obtained as the output SE of the tracking deviation from.

Here, the level of the reproduction pilot signal of frequency f ₂ is g ₂
Since / (g ₁ −g ₂ ), Lb = La × g ₂ / (g ₁ −g ₂ ), and a / b = g ₂ / (g ₁ −g ₂ ), so b · Lb = a ・ La
Therefore, the area of the positive part and the area of the negative part of the output SE become equal. The same applies to the other periods c.

Since the time constant of the tracking servo is sufficiently longer than the cycle of the signal RFSW, the integrated output of the signal SE becomes 0. That is, the tracking servo causes the heads HA and HB to be in the scanning state as shown in FIG.

When changing from playback mode to recording mode,
Based on the contents of the signals SL ₁ and SL ₂ stored when the switch control circuit (40) is paused on, the cyclic continuity of the pilot signal is maintained at this joint as well.

The pilot signal generation circuit (23), switch circuit (24), and switch control circuit (40) are also used during recording. At this time, the frequency is f ₁ → f ₂ → f from the switch circuit (24). _The pilot signal is cyclically obtained as ₃ → f ₄ → f ₁ and is recorded.

Therefore, when the recording state is changed to the pause state, the pause state is released thereafter, and the recording is continued, the switch switching signal SL when the pause is turned on is performed in the same manner as described above.
₁ and SL ₂ are stored in the switch control circuit (40), and the continuity of circulation of the recording pilot signal is maintained based on the stored contents when the recording state is resumed.

〔The invention's effect〕

As described above, according to the present invention, in the reproduction mode for the tape return amount at the time of continuous recording, the tracking phase is shifted from the normal just tracking position in the forward direction,
Since the ends of the recording tracks in the width direction and the ends of the gap of the rotary head in the width direction are aligned with each other, there is no disadvantage that the width of the last track of the recorded tracks at the joint becomes narrow. Therefore, during reproduction, the S / N does not deteriorate and the vertical synchronization is not disturbed at this joint.

Moreover, in order to shift the tracking position like this,
It is very simple to control only the order of supply of the reference pilot signal to the multiplication circuit and the switching time.

[Brief description of drawings]

FIG. 1 is a track pattern diagram for explaining the features of the present invention, FIG. 2 is a track pattern diagram for explaining the effect, and FIG. 3 is a block diagram of an example of the device of the present invention.
FIG. 4 is a diagram for explaining the same, FIG. 5 is a diagram for explaining the joint recording, and FIG. 6 is a diagram for explaining a recording track pattern when tracking control is performed only by the rotary head without using the fixed head. FIG. 7 is a block diagram for explaining an example of the tracking control, and FIG.
FIG. 9 is a diagram showing a timing chart for the explanation, and FIGS. 9 to 11 are diagrams for explaining the conventional defects. HA, HB are rotary heads, T ₁ , T ₂ , T ₃ , T ₄ are recorded tracks, (T
_The tracks ₁ ), (T ₂ ), (T ₃ ), and (T ₄ ) are connected and recorded.

Claims (1)

[Claims] 1. A rotary head having a gap width wider than a track width for recording an information signal on a tape diagonally without forming a guard band, and a rotary head superposed on the information signal, Circuits for cyclically recording pilot signals of four different frequencies for each track, and for tapes with a recorded portion, when recording by connecting to the recorded portion, press the pause switch A means to put the tape in a pause state after rewinding it by a predetermined amount from the position, and a playback position tracking control of the rewound predetermined amount of tape portion when the pause is released, and the tape position when the pause switch is pressed. A recording device provided with means for starting recording from the reference pilot signal generating means for generating reference pilot signals of the four different frequencies; A switch means for selecting one of the output signals from the quasi-pilot signal generating means, a switch control means for controlling the switch means, and a first means for detecting an amplitude of a frequency difference component between the reference pilot signal and the reproduction pilot signal. And second detection means,
A subtraction unit for detecting a difference between the output of the first detection unit and the output of the second detection unit; and a phase servo unit for controlling the phase of the drive motor of the rotary head by the output of the subtraction unit, In the first mode in which normal recording and reproduction are performed, the switch control means cyclically allocates the pilot signals of the four different frequencies for each half cycle of the head switching signal, and from the pause release to the recording start. In the second mode for reproducing the period, the half cycle of the head switching signal is divided into the first and second periods, two different frequencies are assigned to these periods, and four sets of different frequencies are provided for each half cycle. Means for controlling the switch means so that one set of the rotary heads is cyclically assigned, and the ratio of the half cycle period of the head switching signal to the first period is the gear of the rotary head. The ratio between the gap width and the width of the gap part that straddles the adjacent track when the gap end coincides with the track end is set so as to have a constant relationship. During the period, the reference pilot signal is used to perform the tracking control so that the end of the information signal track on the tape transfer direction side in the width direction and the end of the rotary head gap in the width direction coincide with each other. When the tape position when the pause switch is pressed is switched to the first mode and the four different pilot signals are cyclically recorded, the cyclic continuity of the pilot signals is improved. A recording apparatus, characterized in that the switch means is controlled so as to be maintained at a joint with a recorded portion.