JPS6028020A - Information recording and reproducing device - Google Patents

Abstract

PURPOSE:To correct easily and accurately a tracking error without deteriorating the information recording density by separating two signals which are reproduced via a head gap into the information and control signals and comparing these two signals with each other. CONSTITUTION:The reproduced signals are separated into information and control signals, and two control signals separated by BPF7a and 7b feed two envelope signals S1 and S2 to a differential amplifier 12 via envelope detecting circuits 10 and 11. A tracking error detecting means consists of the circuits 10 and 11 and the amplifier 12. The polarity and the level of an output signal S0 of the amplifier 12 show the direction and the value of a tracking error. Then the signal S0 is supplied to a head driving means 14, and an information reproduction head 3 is driven toward the track width in order to correct the tracking error. In such a way, a tracking error can be corrected easily and accurately without deteriorating the recording density.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention records information on an information recording medium using a multi-track information head having a plurality of head gaps corresponding to a plurality of information recording tracks, and reproduces the recorded information. Regarding information recording and reproducing devices such as data recorders,
In particular, it relates to tracking control when reproducing the information.

In an information recording/reproducing device such as a data recorder,
In order to increase the recording density of information, information recording media (generally magnetic tape, henceforth simply referred to as "tape") are used.
A large number of information recording tracks are formed.

Therefore, unless tracking is performed so that the positional relationship of each head gap of the multi-track information head with respect to the tape width direction always matches during information recording and playback, the level of the information playback signal due to each head gap will increase. The information may fluctuate or the crosstalk between tracks in the reproduced signal may increase, and in extreme cases, information on a track different from that at the time of recording may be reproduced, making it impossible to reproduce accurate information.

Therefore, the easiest way to track is
Generally, a guide made of a hard material is provided to restrict the movement of the tape in the width direction while it is running.
Because the edge of the tape was always in contact with the guide, it was easily damaged, and accurate tracking was not possible.

Therefore, attempts have been made to correct tracking by using a wobbling method or a method in which control signals are recorded on a dedicated track as a method for performing tracking without using a tracking tape guide.

The wobbling method is described, for example, in JP-A-56-117.
As described in Publication No. 328.

Tracking is performed by reproducing information by wobbling the information reproducing head at a constant period with a width smaller than the width of the information recording track, and by envelope detecting the reproduced signal from the amplitude and phase of the wobbling frequency component of the signal. This method detects the magnitude and direction of the error and drives the reproducing head in the width direction of the track to correct the tracking error.

However, in this method, the information reproducing head always swings in the width direction of the track during information reproduction, so it is essentially unsuitable for high-density recording with a small track interval.

In addition, a method of recording control signals in a dedicated trunk is to play back the signals by tracing each half width of the track in which the control signals are recorded on the information playback head in the width direction. A pair of head gaps is provided, and the size and direction of the tracking error are detected based on the magnitude relationship of the signals detected by each head gap, and the playback head is driven in the width direction of the track so as to correct the tracking error. It's a method.

However, in this method, the provision of dedicated tracks for tracking that cannot be used for recording information itself goes against the requirements for high-density recording.

The present invention eliminates the drawbacks of the conventional tracking correction method in the information recording and reproducing apparatus as described above, and provides an information system that allows tracking errors to be easily and accurately corrected without sacrificing information recording density. The purpose is to provide a recording/playback device.

Structure Therefore, the information recording and reproducing apparatus according to the present invention records a control signal in a guard band between a plurality of tracks of an information recording medium, and when reproducing information, the control signal of the head that reproduces the information (multi-track information head) is used. The two reproduced signals reproduced through head gaps corresponding to a pair of information recording tracks along both ends of the recording width are separated into an information signal and a control signal, and the two separated control signals are compared. The apparatus is provided with various means for detecting the magnitude and direction of the tracking error and driving the head in the width direction of the track so as to correct the tracking error.

LOL''L■ Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1(a) shows an example of the arrangement of an information head and a control head in an information recording/reproducing apparatus according to the present invention.
b) and (c) show the relationship between the head gap of each head and the recording pattern (track) on the tape, which is an information recording medium.

As shown in these figures, tape 1, which is an information recording medium,
The information recording head 2 is moved along the running direction (arrow A direction).
．． Information playback head 3. A control head 4 for recording control signals is disposed at a position preceding these.

The information recording head 2 and the information reproducing head 3 are both multi-track information heads having a plurality of gap gaps ALB, C, old, etc. corresponding to a plurality of information recording tracks, Information recording track'r
,,T2. An information signal is recorded on . . . and the recorded signal is reproduced.

In this embodiment, the control head 4 has a head gap g having a slightly wider track width corresponding to the guard band G between the first track T and the second track T2, and has a head gap g having a track width slightly wider than the guard band G between the first track T and the second track T2. Control signals are recorded so that they partially overlap (in the example shown, they overlap about half the track width).

This control signal is a signal that can be separated from the information signal, for example, M or N outside the frequency band W of the information signal shown in FIG.
It is assumed that the signal has a frequency of approximately constant level as shown in .

After recording the control signal by the control head 4,
By recording the information signal (digital signal) in double writing form using the information recording head 2, the portion of the recorded control signal that overlaps with the track T I + T 2 is erased, and only the portion of the guard band G is recorded. remain.

At this time, even if the tape 1 swings slightly in the width direction and a tracking error occurs between the control signal recording track and the information recording track, both ends of the control signal recording track in the width direction Since it is erased by writing, the recording width of the control signal is equal to the head gap a of the information recording head 2.
, b and becomes constant.

When the tape on which control signals and information signals have been recorded in this way passes over the information reproducing head 3 and the information is reproduced, if there is no tracking error, the signals reproduced by the head gaps a and b Both are information signal components only. When the information signal is recorded as a digital signal, the level of the envelope of the reproduced signal is also approximately constant.

However, when a tracking error occurs, a control signal is mixed in with the information signal in the signal reproduced by head gaps a and b of information reproducing head B, and head gap a
The ratio of the information signal component and the control signal component S of the reproduced signal due to
Changes as shown in a) and (c).

Therefore, if only the control signal component S of the reproduced signals due to the head gaps a and b is separated and its envelope is detected, the result will be as shown in FIGS. 3(b) and 3(d), respectively.

That is, when the tape 1 shifts upward in FIG. 1(b),
The control signal component S is mixed into the reproduced signal due to the head gap a, and when it shifts downward, the control signal component S is mixed into the reproduced signal due to the head gap b.

The magnitude of the control signal component S corresponds to the magnitude of the tracking error.

Therefore, by comparing the control signal components of these two reproduced signals, the magnitude and direction of the tracking error can be detected, and the tracking error can be corrected.

Next, an example of a tracking control circuit for correcting tracking errors as described above will be explained with reference to FIG.

In FIG. 4, 5 is a head amplifier, 6a and 6b are bandpass filters that have band characteristics that allow only the frequency components of the information signal to pass, and 7a and 7b are bandpass filters that have band characteristics that allow only the frequency components of the control signal to pass. 8 is a waveform equalization circuit, 9 is a demodulator, 10°11 is an envelope detection circuit,
12 is a differential amplifier.

Reference numeral 13 is an amplifier, and 14 is a head drive means using a small electromagnetic actuator or the like.

According to this circuit, the reproduction signal from each head gap a-n of the information reproduction head 3 is transmitted to each head amplifier 5.
After being amplified by the head gaps d and b for reproducing the information recording tracks along both ends of the guard band in which the control signal is recorded, the reproduced signals by the head gaps d and b are amplified by bandpass filters 6a and 78 and 6b and 7b, respectively, which are signal separation means. It is separated into signals and control signals, among which information signals are
Together with the reproduced signals from other head gaps, they are input to the demodulator S through the waveform equalization circuit 8, demodulated, and output as a digital information signal.

The envelopes of the two control signals separated by the bandpass filters 7a and 7b are detected by envelope detection circuits 10.11, for example, as shown in FIG. 3(b).
and two envelope signals S as shown in (d),
, S2 are input to the differential amplifier 12.

The differential amplifier 12 compares the magnitude relationship of the input signals S, , S2, sets the output to zero when Sl = S2, and outputs a positive signal corresponding to the difference when Sl = S2, and outputs a positive signal to S2. When the difference is large, a negative signal corresponding to the difference is output.

This envelope detection circuit 10.11 and differential amplifier 12
The tracking error detection means is constituted by the tracking error detection means, and the polarity and magnitude of the output signal So of the differential amplifier 12 indicate the direction and magnitude of the tracking error.

Therefore, this signal So is amplified through the amplifier 13 and supplied to the head driving means 14, and the information reproducing head 3 is driven in the width direction of the track so as to correct the tracking error.

That is, corresponding to the example shown in FIG.
The tracking error can be corrected by moving the information reproducing head 3 upward when the value is positive, and by moving it downward when the value is negative.

FIG. 5 shows the relationship between the magnitude of the control signals Ss and S2 (S2 is inverted and shown as S2) output from the envelope detection circuits 10 and 11 and the amount of tracking error. In (a), the track width when recording by information recording head 2 and during reproduction by information reproducing head B is the same; (b)
(e) shows a case where the track width during recording is wider than that during reproduction, and (e) shows a case where the track width during reproduction is wider than that during recording.

In the cases of FIGS. 5(,) and (c), it is clear that the information reproducing head can be corrected to a position without tracking error by the circuit of FIG. 4, but in the case of (b), Since the control signal 5ItS2 is all zero between the point and the point H, the head position is not corrected.

However, at point I in FIG. 5(b), the information recording track T1. The positional relationship between T2 and the head gaps a and b of the information reproducing head 3 is as shown in FIG. 6(a), and the point (■) is as shown in FIG. 6(b).

That is, during this period, head gaps a and b are both within the width of the information recording tracks 'rt, 'r, . . . , so there is no difference in the reproduction of the information signal no matter where they are located.

In the circuit shown in FIG. 4, the bandpass filters 6a and 6b for separating the information signal are bandpass filters that pass only the frequency component of the information signal, but as shown in FIG. A band eliminator 6 that only removes the rays may be used.

In addition, in a state where almost no tracking deviation occurs, the reproduction level of the control signal becomes small, so the S/N
In some cases, this may deteriorate and result in unstable control operations.

As a countermeasure for this, for example, as shown in Figure 8, a dead band circuit consisting of a DC power supply E, a diode D, and a resistor R is added to each of the two control signal regeneration systems, so that extremely small level signals are You may choose not to let it through.

However, if the degree of tracking deviation corresponding to this dead zone level is sufficiently small relative to the tracking error correction amount, the same effect can be obtained even without adding a dead zone circuit.

Generally, a sufficient effect can be obtained if the information signal system has a sufficient S/N ratio with almost no tracking deviation occurring. At this time, it is also possible to improve the S/N by narrowing the passband characteristics and steepening the cutoff characteristics of the bandpass filter for separating the control signals.

By the way, the recording width of the control signal is not limited to between two adjacent information recording tracks, but may be recorded with a width that spans more information recording tracks, but in that case, both ends of the recording width The control signal is separated from the reproduction signal due to the head gap that reproduces the information recording track along the head gap.

Moreover, without providing the control head 4 in the information recording/reproducing device,
A similar effect can be obtained by using a recording medium in which control signals are recorded in advance at predetermined positions on the tape.

In the above-described embodiment, the information recording head and the information reproducing head are provided separately, but it goes without saying that the present invention can also be implemented in an information recording/reproducing apparatus having an information head that is integrated with the information head and serves for both recording and reproducing purposes. Furthermore, the present invention is not limited to those using magnetic tape as the information recording medium, but is also applicable to those using various information recording media such as disk-shaped, sheet-shaped, card-shaped, etc.

- As explained above, the information recording/reproducing apparatus according to the present invention does not require wobbling of the information reproducing head or use of a dedicated track for recording tracking control signals. Since the direction and magnitude of the tracking error during information reproduction can be easily and accurately detected and corrected, it is extremely effective for narrowing the track spacing and increasing the information recording density.

[Brief explanation of drawings]

FIG. 1(a) is a layout diagram of each head in an embodiment of the present invention, FIG. 1(b) is an explanatory diagram showing the relationship between the head gap of each head and the recording pattern on the recording medium, and FIG. 1(c) is the same main part. FIG. 2 is an enlarged view showing the tape in an enlarged manner only in the width direction of the tape. FIG. 2 is a diagram for explaining an example of the difference in frequency bands between an information signal and a control signal, FIG. 3 is a signal waveform diagram for explaining the principle of tracking error detection in this invention, and FIG. FIG. 2 is a block circuit diagram showing a tracking control circuit in an embodiment of the invention. 5(a), 5(b), and 5(c) are diagrams showing the relationship between the magnitude of two control signals and the amount of tracking error, each having a different track width relationship during recording and reproduction, and FIG. 6(a). )(b) is an explanatory diagram showing the positional relationship between the information recording track and the head gap of the information reproducing head at points 1 and ■ in FIG. 5(b), respectively. 7 is a block diagram showing a different example of the bandpass filter in FIG. 4, and FIG. 8 is a partial circuit showing an example in which a dead band circuit is added to each of the two control signal reproducing systems in FIG. 4. 1... Magnetic tape (information recording medium) 2... Information recording head 3... Information reproducing head 4.
...Control head 5...Head amplifier 6.6a, 6b
...Band filter for information signal separation 711897b...
・Band filter for control signal separation 10.11...Envelope detection circuit 12...Differential amplifier 14...Head driving means Fig. 1 Fig. 2 Fig. 3 Fig. 5 Fig. 6 (Q) (b ) Figure 7 Figure 8

Claims (1)

[Claims] 1. A multi-track information head having a plurality of head gaps corresponding to a plurality of information recording tracks,
In an information recording and reproducing device that records information on an information recording medium and reproduces the recorded information. control signal recording means for recording a control signal on a guard band between a plurality of information recording tracks of the information recording medium; and a pair of information recording tracks along both ends of a recording width of the control signal of the information head during information reproduction. Signal separating means for separating two reproduced signals reproduced through corresponding head gaps into an information signal and a control signal, and tracking for detecting a tracking error by comparing the two control signals separated by the means. An information recording and reproducing device characterized in that it is provided with an error detecting means and a head driving means for driving the information head during information reproduction in the track width direction so as to correct a tracking error according to the detection result by the means. Device. 2. The control signal recording means straddles two adjacent information recording tracks of the information recording medium so as to partially overlap each other, by means of a control head provided at a position preceding the information head with respect to the running direction of the information recording medium. 2. The information recording and reproducing apparatus according to claim 1, further comprising means for recording a control signal on a guard band between the two information recording tracks. 3. A patent claim in which the control signal recording means is means for recording a control signal with a frequency component different from the frequency component of the information signal, and the signal separation means is a plurality of bandpass filters that separate the control signal and the information signal according to their frequency components. range 1
The information recording and reproducing device according to item 1 or 2. 4. The tracking error detection means includes an envelope detection circuit that detects the envelopes of the two control signals separated by the signal separation means, and a tracking error detection circuit that detects the envelopes of the two control signals separated by the signal separation means, and a Claims 1 to 3 consist of a differential amplifier that outputs signals of polarity and magnitude.
The information recording and reproducing device described in Section 1.