JPS63237247A - Recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain tracking at the time of reproduction with a simple circuit constitution by fitting plural rotary heads reproducing one and the same track on a rotary drum with a step and obtaining information on track deviation at the time of reproduction from an output difference with respect to one and the same track of the rotary heads. CONSTITUTION:When the heads HA and HA' fitted to the rotary drum 1 with a step PS are reproduced, the difference of the track in deviation directions is represented as the size of the outputs of the heads HA and HA'. Here, envelope detection circuits 6 and 7 are provided on the output side of reproduction amplifiers 2 and 3, and the level of reproduction signals is detected. The detection outputs SA2 and SA2' of the circuits 6 and 7 are supplied to sampling hold circuits 8 and 9 and are subjected to a sample-and-hold. The sampling-holding signals SA3 and SA3' are transmitted to the non-inverted input terminal and the inverted input terminal of a comparator 10, and comparison error signals are fetched to a terminal 11 as tracking error signals SE.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a recording/reproducing device suitable for use in, for example, a video tape recorder (VTR) or a digital audio tape recorder (DA'l').

[Summary of the invention]

The present invention provides a rotary head type recording and reproducing device that includes:
At least two or more rotary heads that play the same track are installed on the rotary drum with a step difference so that the trajectory forces against the tape do not match, and track deviation information during playback is obtained from the output difference of the rotary heads for the same track. By rubbing G to obtain , it is possible to perform 1-racking during playback with a simple circuit configuration without using a special tracking/knocking signal.

[Conventional technology]

In the playback mode of a normal rotating head type recording/playback device,
The tape speed is controlled so that the head and throat correctly trace the recording pattern on the tape.

of the head against the recording pattern! In order to perform tracking control by detecting the deviation of the TiIL trace (track deviation), a control (CTL) head as a fixed head is used to record the CTL in the longitudinal direction of the tape, and this is detected during playback to perform tracking control. The CTL method performs knocking control, and the ATF method performs tracking control by recording a special signal for tracking on tracks recorded diagonally.
This ATF method is, for example, P in the case of DAT.
When recording a CM signal by compressing the time axis and forming a trunk diagonally on a recording medium using multiple rotary heads without forming a guard band, the PCM signal is recorded in the longitudinal direction of each track as a recording area. Multiple pilot signals for tracking are recorded independently, and during playback, the recording track is scanned by a rotating head whose scanning width is wider than the width of the track, and the pilot signals are reproduced from trunks on both sides of the track being scanned by the rotating head. The tracking of the rotating head is controlled by the output.

Furthermore, as a simple method, it is also possible to perform tracking control by detecting the output level itself of the reproducing amplifier and detecting trunk deviation from its increase or decrease.

[Problem that the invention seeks to solve]

By the way, in the case of the above-mentioned conventional methods, there are various drawbacks as follows. First, in the case of the C'T'L method, a dedicated fixed head is required, separate adjustment is required, and sometimes an erasing head is also required, and there are limits to miniaturization.

Further, in the case of the ATF method, it is necessary to separate the signal from a video signal or an audio signal, and there are drawbacks that the circuit configuration or the frequency band used is limited.

In addition, in the case of a method that detects the output level itself of the playback amplifier, since the absolute level changes when the type of tape is different, it is first necessary to find the output peak, and moreover, it is necessary to find the output peak first, and the direction of track deviation ( It is not easy to find out the positional relationship between the track and the head.
As a result, complex control is required.

In addition, in a 4-head type recording/playback device, there are systems in which two heads for one trunk are dedicated to recording and playback, respectively, or a system in which both heads are used as a cover, but in either case, one trunk can be used for two heads. I'm sure two heads will trace it. In addition, in the guard pan dress azimuth record,
Since the track width of the head is generally wider than the recording 1-rack width, a certain amount of track deviation may be allowed before the output level decreases. Therefore, it is possible to effectively utilize this tolerance and the fact that the two heads trace the same track.

This invention was made in view of this point, and it is not necessary to record a special signal for tracking on the tape, and it is possible to perform simple playback tracking that detects track deviation based on the playback signal. The present invention provides a recording/playback device.

[Means for solving problems]

The present invention provides a rotary head type recording and reproducing device that includes:
It has at least two or more rotary heads F18, H8' (or HB, HB') for reproducing the same track,
These rotating heads are mounted on the rotating drum (1) with a step difference of 1]s so that the TDT marks on the tape do not match. It is configured to obtain deviation information.

[Effect]

At least two or more rotating heads HA+)(A'(or I(B, I(B')) that play the same track are moved to a rotating drum (1) so that their trajectories with respect to the tape do not match.
) with a predetermined step Ps above. That is, P
Let s = 1/2 P7 +PH. However, I) T is the recording track width, and Ps is the pitch of the trajectory of the head on the tape. The rotating head i (A
, ) (By scanning the same track with A' (or HB, H,'), the difference in the direction of track deviation can be detected by both heads H.
This is expressed as a magnitude relationship between the outputs of A and H' (or H8 and HB'). As a result, the rotating head HA+ H^'(
Track deviation information during playback can be obtained from the output difference between the signals (or HB, Hs'), and tracking during playback can be performed with a simple circuit configuration without using a special tracking signal.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail based on FIGS. 1 to 13.

First, the basic principle of this invention will be explained using the case of guard panless azimuth recording method 4-head type as an example, and FIGS.
This will be explained with reference to FIG.

Fig. 9 shows an example of the arrangement of the heads of a four-head drum.The rotating healds H^ and Hm are spaced equiangularly, that is, at an angle of 180°, as shown in Fig. 9. The rotating heads HA' and HB' are likewise arranged at the periphery of the rotating drum +1) with an angular spacing of 180°. Heads f (8 and HR and HΔ' and I8' have different azimuth angles and trace different tracks from each other, and heads I (A and I
] Δ' and heads Ha and l (day') have the same azimuth angle and trace the same track.Here, for example, head H is used for both recording and playback, and head H
A' and HRI are used only for reproduction.

Therefore, during recording, heads HA and H8 are used to form diagonal magnetic tracks one by one on the magnetic tape, for example in a so-called overwritten state, to obtain a recording pattern as shown in FIG. 1O.

When the heads HA, HR, HA', and H8' are mounted on the rotating drum (1), if they are mounted on the same surface of the drum, that is, if they are mounted with zero step, the heads HA, HA', 8' is as shown in Figure 11. That is, during recording with heads H^ and HR, playback-only head I (A' and HB' move slightly with respect to the trajectory of heads HA and H8). In FIG. 11, W represents the track width of the head, PT represents the width of the recording track, and the trunk width WH of the head is normally larger than the recording trunk @PT, about 1.5 times.

By the way, in order to perform so-called simultaneous recording by reproducing what is recorded with heads H^' and HB' after recording with ordinary heads H^' and HB', a difference in mounting level is provided between the same azimuth heads, and the playback track level difference screw is installed. i-correction may be performed. FIG. 12 shows the case where this reproducing track level difference correction is performed, and as can be seen from FIG. 12, the trajectories of heads H^ and HA' and heads H8 and HB' coincide. FIG. 12 also shows the case where dedicated heads are used for recording and reproduction.

In this case, the mounting step Ps between the same azimuth heads is P
It is set to s=1/2PT. In addition, the head H^1.
The mounting may be stepped so that the HB/ traces each adjacent track with a further delay. Expressing this in the general formula, Ps = (2n+ 1/2) Pt
becomes. However, n is n=o, 1.2.3...

Figure 13 shows a situation in which when the playback head track @WH is wider than the recording track @P, it appears that no track misalignment has occurred on the output, even though there is actually a track misalignment. It is something that In other words, in FIG. 13, even if the head (above 1) (A) is completely in line with the trunk (just track), the middle and bottom heads 11Δ are shifted to the left and right,
However, the reproduction outputs obtained from the heads HA of these funds are the same, and it appears that no track deviation occurs even in the case of the middle and bottom heads 14Δ. Therefore, the distance between the center and the center of the bottom head H^ at this time is called the tracking margin -1'l, and during this period, even if track deviation occurs, the output level does not change and tracking is achieved electrically. There will be.

Now, in this invention, two heads trace the same track in a four-head type recording/reproducing device, and in guard panless azimuth recording, the track width WH of the head is wider than the recording track width PT, and the output level is Focusing on the fact that a certain amount of track deviation is allowed before the track deviation decreases, two heads HA and HΔ' (or He and He') tracing the same track are set to a predetermined step Ps as shown in FIG. Holding the tape and attaching it to the rotating head (1) is the same as in the case of track level difference correction explained in FIG. As shown in Fig. 6, the rotating head (1
). In other words, the step P at this time
s is set to Ps = 1/2 PT+pH.

Therefore, FIG. 7 shows the relationship between the recording pattern and the head position in several cases when the heads H^ and HB, which are attached to the rotating drum fl+ with a predetermined step PS, are reproduced together. The respective outputs corresponding to this are shown in FIG.

In Fig. 7A, the head H is in the on-trunk state, but
The head r-rA' is in an off-track state, and the reproduced signals s8 and S' at this time are the reproduced signal S^ of the head H^ and the reproduced signal S^' of the head H', as shown in the 8th prisoner. , and this relationship holds as long as heads H^ and I]^' are both shifted to the left.

In Fig. 7B, the head) (A and HΔ' are both off track, but both are in the on-trunk state, and the output shows a state where no track deviation has occurred, and the tracking margin is as shown in Fig. 13. At this time, the reproduced signals SA and S of head !(^ and 1(8') are at the same level at maximum, as shown in FIG.

In FIG. 7C, the head [l^' is in the on-trunk state, but the head HA is in the off-track state, and the reproduced signals SA' and SA at this time are as shown in FIG. 8C.
(The reproduced signal SA' of 8' is larger than the reproduced signal SA of head HA, and this relationship is maintained as long as heads HA' and [18 are both shifted to the right.

It can be seen from FIGS. 7 and 8 that the difference in the direction of track deviation is expressed as the magnitude relationship between the outputs of both heads HA and HA'. In other words, when the track shifts to the right (corresponding to FIG. 7A where heads HA and HA' shift to the left), the playback signal SA of head ItΔ and the head HA
The magnitude relationship of the reproduced signal SA' of head IIA is SA>SA', and when the track shifts to the left (corresponding to FIG. 7C where heads HΔ and HA' shift to the right), the reproduced signal SA of head IIA and the head The magnitude relationship of the reproduced signal SA' of I-1Δ' is SA x S'.

Then, by comparing the reproduced signals SA and S, the comparison error signal can be used as a tracking error signal. In other words, the direction of track deviation can be determined from the magnitude relationship of the reproduced signal SA(!:SA'), and the amount of track deviation can be determined from the difference between them, so that it can be used as a tracking error signal.

Figure 1 shows the circuit configuration of this embodiment, where 1 (^ and HA' are rotating heads with the same azimuth, and their navels).11 A and HΔ' are carved on the tape as described above. The heads I]^ and H are attached to the rotating drum C1) with a predetermined step PS so that their trajectories do not match.
The signals sA and S, which are respectively reproduced by A', are amplified by the reproduction amplifiers (2) and (3) to become the signals SA□ and SAf, which are then taken into the memory of the signal processing circuit (4), and then The signal is read out, subjected to signal processing such as error δ1 positive, etc. as necessary, and sent to the output terminal (5) as a reproduced output signal SPR.
) is taken out. This signal system is a circuit system for obtaining a normal main reproduction output signal.

In this embodiment, envelope detection circuits (6) and (7) are provided on the output sides of the reproduction amplifiers (2) and (3), respectively, to detect the level of the reproduction signal. Detection outputs SA2 and S of these envelope detection circuits (6) and (7)
A6 is supplied to the sample holes [circuits (8) and (9), respectively, where it is sampled and held. These sampled and held signals S^3 and SA4 are sent to a comparator circuit (10
) is supplied to the non-inverting input terminal and the inverting input terminal of the tracking error signal SE, and its comparison error signal is taken out to the output terminal (11) as the tracking error signal SE.

Here, the tracking error signal SI! obtained at the output terminal (11)! has positive polarity when the signal SA3 is greater than S, that is, when the reproduced signal SA to head H is greater than the reproduced signal SA' of head I (A'), and conversely, when the signal SAS is greater than sAi, that is, when the reproduced signal SA to head H When the reproduced signal S^' of ' is larger than the reproduced signal SA of the head HA, it has a negative polarity, and from this the direction of the track deviation can be determined.The difference between the signals S^3 and SA4 can also be used to determine the amount of track discrepancy.

Figures 2 to 4 show the relationship between the tracking error signal St and the track deviation obtained in this way, respectively.
Depending on the pitch P)l on the tape trajectory of the azimuth head, its output can be divided into three types as shown in FIGS. 2 to 4. That is, FIG. 2 shows the case of P<WH-p, FIG. 3 shows the case of PH=WHPT, and FIG. 4 shows the case of PH>WHPT. For example, in DAT, WH
= 1.5PT, so in such a case, it is desirable to set the value of PH between O<<PH≦0.5P. In Figures 2 to 4, when the reproduced signal is SA>SA', the track deviation is in the right direction, and the tracking error signal at that time is positive and increases approximately in proportion to the track deviation; The reproduced signal is sA<s
It can be seen that at A', the tracking error is in the left direction, and the tracking error signal at that time has a negative polarity and decreases approximately in proportion to the tracking error.

In FIG. 2, TM is a dead zone of track deviation caused by the amount of step PsO in head mounting, which occurs when the reproduction signal of head HA and the reproduction signal of head HΔ' are equal, as shown in FIG. 7B. This dead zone T of track deviation
M has the relationship TM=wH-pt-PS, which is useful depending on the servo system. Here, in order to set TM=O, it is sufficient to set PS=WH-PT. This is the case in FIG.

If the tape trajectory pitch PH of the heads is too large, both heads will not be on track,
Tracking error (when the word is zero, i.e. 5A)
= SA'), each head and throat are equally off-track. The characteristics at this time are shown in FIG. This also occurs when wH=pT in recording/reproducing with guard hand, etc. Note that in Figures 2 and 3, the level of one reproduced signal is constant and the level of the other reproduced signal decreases, but in Figure 4, the part where the slope of the characteristic is steep (the sensitivity In the region 1'M') where the signal increases, when the level of one reproduced signal increases, the level of the other reproduced signal decreases, and thus the tracking sensitivity can be increased. The region 'l'H' where the sensitivity increases at this time is expressed as 'I''M'=PH-(WHPT).

In this way, in this embodiment, tracking can be performed using only the reproduction signal without recording a special signal for reproduction tracking. Furthermore, since the level difference is checked, there is no need for any particular adjustment on the playback device side even if the tape has a different recording level, and the direction and amount of track deviation can also be known. Furthermore, since signals obtained by reproducing the same track are compared, it is less susceptible to level fluctuations between tracks.

In addition, although the above-mentioned Example was demonstrated taking the case of guard bandless as an example, it is applicable similarly to the case with a guard band.

〔Effect of the invention〕

As described above, according to the present invention, at least two or more rotary heads that reproduce the same track are mounted on the rotary drum with steps so that their trajectories with respect to the tape do not match, and the output of the plurality of rotary heads for the same track is adjusted. Since trunk shift information during playback is obtained from the difference, tracking during playback is possible with a simple circuit configuration without using special trunking signals, simplifying the circuit configuration and reducing costs. This can be achieved without any restrictions on the configuration or the frequency band used.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram showing one embodiment of this invention, FIGS. 2 to 4 are diagrams for explaining the operation of FIG. 1, and FIGS. 5 to 13 illustrate the basic principle of this invention. It is a figure for explaining. Tl) is a rotating drum, (2) and (3) are playback amplifiers,
f61. (71 is the envelope pixel eclipse circuit, (8),
(9) is a sample bold circuit, and HA I HA' is a rotating head.

Claims (1)

[Scope of Claims] A rotary head type recording/reproducing device having at least two or more rotary heads for reproducing the same track, the rotary heads being mounted on a rotary drum so that the trajectories of the rotary heads relative to the tape do not match. A recording and reproducing apparatus, characterized in that the rotary head is mounted with a step difference, and track deviation information during reproduction is obtained from the output difference of the rotary head for the same track.