JPH01102764A - Tracking error detector - Google Patents

Abstract

PURPOSE:To accurately perform tracking control by detecting the amplitude difference of reproducing signals by two magnetic heads with different azimuth angles, and detecting a tracking error. CONSTITUTION:The tracking error is detected by providing a pair of two magnetic heads, first and second magnetic heads 101 and 102 whose azimuth angles are different and also with width larger than each recording track, and detecting a level difference between the reproducing signals by the first and second magnetic heads 101 and 102. Therefore, at the time of reproducing a recorded information signal by a pair head 1, it is possible to obtain a tracking error signal including information with respect to the direction and the size of the tracking error. In such a way, the tracking control can be performed accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a tracking error detection device, and in particular, it detects tracking errors when reproducing information signals recorded by a pair of magnetic heads (pair heads) that scan simultaneously. The present invention relates to a device for detecting.

In conventional technology recording and reproducing devices, for example, magnetic recording and reproducing devices,
When reproducing an information signal recorded on a recording track, tracking control is required so that the reproducing head on-tracks and performs reproduction scanning on the recording track.

Practical tracking control methods include a dedicated control track in the longitudinal direction of the tape, recording a control signal at a frame period or an integral multiple thereof, and using this control signal during playback. There are known methods of providing tracking control.

The method that has been put into practical use is to record pilot signals for tracking control on the recording track, and during playback, the playback level of each pilot signal read from both adjacent tracks of the main track that the head is scanning for playback. There is a method to obtain a tracking error signal by comparing the In this method, since a tracking error signal can be obtained over the entire recording track, a playback head is mounted on an electro-mechanical transducer composed of a piezoelectric element, etc., and the mechanical position of the head is determined using the tracking error signal. By changing this, it is possible to configure a control system that allows the track music to follow 9.

Another method that has been put into practical use is to swing the playback head in the track width direction at a constant frequency, detect the playback signal, and perform tracking control (using wobbling) to maximize the playback signal output. method) etc.

The above is a general tracking control method.

In addition, when the frequency band of the information signal handled by the recording/reproducing device is wide, there is a method of recording/reproducing the information signal using a set of two magnetic heads (hereinafter referred to as ≧ahead) that scan simultaneously. is valid. because,
When recording an information signal at a constant head scanning speed, the higher the recording frequency of the information signal, the shorter the recording wavelength recorded on the magnetic tape, and the shorter the recording wavelength, the more difficult practical recording and reproduction becomes. This is because if used, the frequency band of the information signal can be divided and distributed to each head, so the recording wavelength can be set substantially longer.

FIG. 6 is a diagram showing the concept of dividing the information signal to be recorded into two types of signals. In the figure, (S-a) indicates the original signal to be recorded, and (5-b) and (S-C) indicate signals obtained by dividing the original signal, that is, actual recording signals supplied to the paired heads.

Original signals 601 and 502 are temporally divided, for example, as shown in the figure, and temporally expanded and divided as shown in 503 and 504. In other words, the frequency band can be lowered by the amount of temporal expansion. In the figure, SOS, 5068507, etc. are timing signals, for example, horizontal synchronization signals. Note that the method of dividing the original signal is not limited to dividing it temporally; for example, there are methods of separating it frequency-wise, and methods of dividing it according to the type of signal, such as a luminance signal or a color signal. .

In any case, when recording a signal with a wide band, the method of using paired heads is practically effective and is a necessary condition.

In a magnetic recording/reproducing device in which two types of information signals divided in this way are recorded on separate tracks by a paired head and reproduced, a tracking error detection device for detecting a tracking error during reproduction is disclosed, for example, in Japanese Patent Application Laid-open No. Showa 6
There is one shown in Publication No. 0-25048. This tracking error detection device is a helical scan type magnetic recording and reproducing device (hereinafter referred to as Y/C separated type VTR) that separates a video signal into a luminance signal and a color signal, records them on separate tracks in a paired head, and reproduces them. This is to detect a tracking error during playback at -t,>.

The conventional tracking error detection device disclosed in Japanese Patent Application Laid-Open No. 60-25046 alternately selects two types of pilot signals with different frequencies for each recording track in a Y/C separation type VTR to detect a video signal. Each of the two types of pilot signals leaks into the output of a magnetic head scanning a track on which no pilot signal is recorded during playback. A tracking error signal is obtained by detecting the amount of leakage.

The problem that the invention seeks to solve However, each of the above methods has the following problems.

First, the method of performing tracking using the control signal described above has drawbacks such as requiring a dedicated control track and not being able to obtain a tracking error signal over the entire recording track.

In addition, in the method of tracking using the pilot signal described above, since it is necessary to record the pilot signal by superimposing it on the information signal, the band of the information signal is reduced by the band of the pilot signal, and the information signal is Signal S/N
The disadvantage is that it deteriorates.

Furthermore, the above-described wobbling-based tracking method detects tracking errors while swinging the reproducing head in the track width direction, which always causes mistracking and cannot perform accurate tracking control.

The conventional tracking error detection device for a magnetic recording/reproducing device that records and reproduces two types of information signals on separate tracks using a pair of heads, as shown in the above-mentioned Japanese Patent Laid-Open No. 6.0-25046, is as follows: Tracking errors are detected by using the pilot signal recorded superimposed on the information signal.As just mentioned, the band of the information signal is reduced by the band of the pilot signal, and the band of the information signal is reduced by the band of the pilot signal. There is a drawback that the S/N of the information signal deteriorates.

Furthermore, as a tracking error detection device for a magnetic recording and reproducing device that records and reproduces two types of information signals on separate tracks using a pair of heads, a method using the above-mentioned control signal and a method using wobbling are also considered, but these methods are not applicable. However, if this method is used, problems unique to each method as described above cannot be avoided.

The present invention eliminates these conventional drawbacks,
To provide a tracking error detection device capable of detecting a tracking error with a simple configuration by taking advantage of the use of a pair head when reproducing a recorded information signal by the pair head.

Means for Solving the Problems The present invention provides at least one set of two magnetic heads, first and second, which have different azimuth angles and are wider than each recording track. This is a tracking error detection device characterized in that a tracking error is detected by detecting a level difference between reproduction signals produced by a second magnetic head.

Operation The present invention has the above-described structure, and the above-mentioned first. By detecting the level difference of the reproduced signal by the second magnetic head,
A signal including information on the direction and magnitude of the tracking error can be obtained, and the tracking error detection device is suitable for a magnetic recording/reproducing device using a paired head.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

In this embodiment, there are two signals, one for simultaneously scanning a luminance signal and a color signal, which are divided from a video signal and recorded on separate tracks.
When playing with a pair of magnetic heads (pair head),
This is a tracking error detection device that detects tracking errors.

First, a pair of magnetic heads, which are the main components of the tracking error detection device of this embodiment, will be explained with reference to FIG.

In FIG. 1, M1+B1. M2IB2. M5+B5
+... are recording tracks recorded on the magnetic tape') -Ai + A2 +A3.・・・・・・
For example, the track group has a brightness signal of B1*82
*For example, a color signal is recorded in each track group of BS. Note that the track group M1.
Mu2. 3...and the track groups Bi, B2
+ BS...Melts are recorded at mutually different azimuth angles.

Reference numerals 101 and 102 designate a pair of magnetic heads (pair heads) that simultaneously scan the magnetic tape in two directions indicated by arrows. That is, the magnetic heads 101 and 102 constitute a pair head 1. 103 and 104 indicate head gaps in each head. Magnetic heads 101 and 102
For example, the magnetic head 101 has track groups AI + A2 * 'S...
Same azimuth angle as...

The magnetic head 102 has track groups B1+B2+B5
It has the same azimuth angle as... moreover,
The magnetic heads 101 and 102 are both wider by Wl than the recording track width Wo, and when the pair head 1 is accurately on-tracking the recording track, the pair head 1 is in the width direction of the recording track. The position will be as shown in Figure 1.

FIG. 2 shows the pair of heads 1, that is, the magnetic heads 101 and 102, which are the main layer components in the device of this embodiment.
FIG. 2 is a block diagram showing a circuit configuration until a tracking error signal is obtained from a signal that is reproduced.

In FIG. 2, 101 and 102 are magnetic heads constituting the pair head 1 explained using FIG. 1, 6.6 is an amplifier circuit, and 7.8 is a detection rectifier circuit, each of which handles input signals. A signal 11.12 having a magnitude proportional to the amplitude is output. Reference numeral 9 denotes a differential amplifier circuit that amplifies the difference between the signals input to each input terminal 91 and 92, and the output terminal 9
3, a signal whose magnitude is proportional to the difference between the signals to each input terminal 91 and 92 is obtained. 1o is a tracking error signal output terminal.

The signals reproduced by each magnetic head 101, 102 are
After each is amplified by an amplifier circuit 5.6, it is detected and rectified by a detection rectifier circuit 7.8, and the output signal 11.12 includes a signal from each magnetic head 101, 1.
A signal corresponding to the amplitude of the reproduced signal of 02 is obtained. In the differential amplifier circuit 9, a signal corresponding to the difference between the signals 11 and 12 is obtained and output to the output terminal 10. That is, a signal representing the amplitude difference between the reproduced signals of the respective magnetic heads 101 and 102 is obtained at the output terminal 10.

FIG. 3 shows the positional relationship between the recording track and the paired head 1 (&) to (7 lines of the ship).

In FIG. 3, AI+MU2. Mu3. ...
..., and B1 * B2 + B5 *...
The recording tracks indicated by ・are simply indicated as A and B, respectively. When the center of the pair head 1 is on the broken line (h), the pair head 1 is in a state of accurately on-tracking the recording track, and this state is shown in the figure ((1).The figure (2L)
), (b), and (C) show the state in which the tracking of pair head 1 is shifted to the right on the paper compared to (d) in the same figure, and (6), (f), and (g) in the same figure show that the tracking of pair head 1 is shifted to the right on the paper. Same figure (
d) shows a state in which the tracking of the pair head 1 is shifted to the left on the paper. On-tracking state (Figure (d), ΔX=O), where the amount of tracking deviation is ΔX
On the other hand, when pair head 1 shifts to the right on the paper, Δ
ヱ〉0, when it shifts to the left, Δe (represented as 0, the figure (
2L) to (g), the tracking deviation amount Δ is (a) ----wo-wo (ΔX≦W.

(b)・・・・・・1+<ΔX≦Wo−w.

(C)...0〈Δwork≦W1(d)...
・・Δ1=0 (e)・・・・−W1≦ΔX<0(f)”・
-(Wa-Wl)≦Δx<-Wl(g)...
Each case of -Wo≦Δx((Wo L) is shown.

FIG. 4 shows the center of the paired head 1 on the recording track (represented as A, B, person, B, A, etc. in this figure as well as in FIG. 3) when changing its position in the width direction. Signals of each part in Fig. 2 (signal 11 and signal 12 and output terminal 10
FIG. 10 is a diagram showing how the signal 10) obtained in FIG.

In (11), (12), and (1o) of FIG. 4, the horizontal axis indicates the center position of the paired head 1 in the recording track width direction, and the vertical axis indicates the output level of each signal.

First, the signal 11 will be explained. Since the magnetic head 101 has the same azimuth angle as the multi-track group, the reproduced signal of the magnetic head 101 has an amplitude corresponding to the length of the portion on the A track of the magnetic head 1o1 in the track width direction. The output signal 11 of the detection rectifier circuit element is obtained as follows.
A signal representing the amplitude of the reproduction signal of the magnetic head 101 is obtained.

Therefore, the output signal 11 of the detection rectifier circuit 7 changes as shown in FIG. 4 (11) depending on the position of the center of the paired head 1 in the recording track width direction.

Next, the signal 12 will be explained. The magnetic head 102 is B
Since the azimuth angle is the same as that of the track group, the reproduced signal of the magnetic head 1o2 has an amplitude corresponding to the length of the portion on the B track of the magnetic head 102 in the track width direction, and the detection rectifier circuit As the output signal 8, a signal representing the amplitude of the reproduction signal of the magnetic head 102 is obtained.

Therefore, the output signal 12 of the detection rectifier circuit 8 changes as shown in FIG. 4 (12) depending on the position of the center of the paired head 1 in the recording track width direction.

Since a signal corresponding to the difference between the signals 11 and 12 is obtained at the output terminal 1o, the signal obtained at the output terminal 10 depends on the position of the center of the paired head 1 in the recording track width direction. The change occurs as shown in Fig. 4 (10).

In addition, in FIG. 4, the explanation using FIG. 3 (a
) to (g), when the tracking deviation Δ has occurred (at this time, the position of the paired head 1 shown in FIG. 4 is assumed to be the on-track position), the position where the center of the paired head 1 can exist. (a) to (g) also correspond to those in Figure 4.
).

The signal 1o obtained at the output terminal 1o shown in FIG. 4(10) will be further explained with reference to the same figure.

As is clear from FIG. 4, when the center of pair head 1 is on track A, signal 1o is negative (less than zero level), and when the center of pair head 1 is on track B, signal 1o is negative. is positive (greater than the zero level).

The fact that the center of pair head 1 is on track A means that the tracking of pair head 1 is shifted to the left on the paper with respect to the on-track position (the closest on-track position). The fact that the center is on track B means that the tracking of pair head 1 is shifted to the right on the paper with respect to the on-track position (the closest on-track position).

In other words, if the tracking of pair head 1 shifts to the left on the paper with respect to the on-track position, the signal 10 will be negative, and if the tracking of pair head 1 shifts to the right on the paper, the signal 10 will be positive. Become. Therefore, the direction of the tracking deviation (tracking error) can be known from the signal 10.

Also, as is clear from Fig. 4, the tracking deviation Δ
When I is in the range -W1≦Δwork≦W1, there is a linear relationship between ΔX and the signal 100 level, so -W+≦Δwork≦W
In the range of 1, the magnitude of the tracking deviation (tracking error) can be determined from the difference between the signal 10 and the zero level.

In this way, the direction of the tracking error and the magnitude of the tracking error in the range -Wi≦Δ1≦W1 can be known from the signal 10.

Therefore, with the device of this embodiment, the signal 1Q obtained at the output terminal 10 can be used as a tracking error signal.

Therefore, for example, if the tracking error signal 10 obtained by the apparatus of this embodiment is negative, the pair head 1 is moved to the right side (for example, on the page of FIG. 4), and the signal 10 is negative.
If the tracking control system is configured so that when is positive, the paired heads 1 are respectively displaced to the left (for example, on the paper of FIG. 4), and the signal 1o is at zero level,
The paired head 1 can perform reproduction scanning while always on-track on the recording track.

Further, tracking control can also be performed by feeding back the tracking error signal 10 obtained by the apparatus of this embodiment to the control system of the capstan motor that drives the magnetic tape and controlling the capstan motor.

The device of this embodiment has been described as a tracking error detection device for a recording track in which a video signal is divided into a brightness signal and a color signal, but the recorded signal is However, the information signal is not limited to this, and may be an information signal that is temporally divided into two and each temporally expanded, or an information signal that is frequency-separated, and the tracking error can be detected in the same way as the device of this embodiment. Can be done.

In addition, the device of this embodiment has a pair of heads 1, which are its main components, as a magnetic head 101, as shown in FIG.
102 is wider than the recording track width WO by an equal length Wl in the opposite direction of the track width direction. Although it is desirable that the margins of each magnetic head width with respect to the recording track width WO be equal, it is not necessary to make them strictly equal, and there may be some error. for example,
If the magnetic head 101 has an error of ±ΔW with respect to Wl, and the magnetic head 102 has an error of ±ΔWB with respect to Wl, the linear region of the magnitude of the signal 10 obtained at the output terminal 1o is -(
W, ±ΔWmu) ≦Δwork≦W1±ΔWs, and the symmetry with respect to the on-track position is lost, but ΔWmu,
If both ΔWB are sufficiently small with respect to Wl, the signal 1o obtained in this case can be sufficiently used as a tracking error signal.

The tracking error signal obtained by the device of this embodiment can be used not only for detecting the direction and magnitude of tracking deviation (tracking error) with respect to the recording track during playback, but also for detecting the direction and magnitude of tracking error with respect to the recorded track during playback. It can also be used to detect the track music of recorded tracks.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, according to the present invention, when a recorded information signal is reproduced by a pair head, a tracking error signal including information on the direction and magnitude of the tracking error can be obtained with a simple configuration. Can be done.

According to the present invention, a tracking error signal is obtained using a signal reproduced by a paired head, and a tracking error signal can be obtained over the entire recording track. Furthermore, since there is no need to record the pilot signal by superimposing it on the information signal, S/N degradation of the information signal due to the pilot signal does not occur. Furthermore, since this method does not involve wobbling, accurate tracking control is possible based on the obtained tracking signal.

Further, the tracking error signal obtained by the present invention can be used not only for detecting the direction and magnitude of a tracking error with respect to a recorded track during playback, but also for detecting the direction and magnitude of a tracking error with respect to a recorded track during recording. It can also be used to detect.

[Brief explanation of the drawing]

FIG. 1 is an auxiliary diagram for explaining the paired head, which is the main groove bottom element in one embodiment of the present invention, and FIG. 2 shows the circuit configuration from the reproduced signal of the paired head to obtaining the tracking error signal in the same embodiment. A block diagram, FIG. 3 is a positional relationship diagram showing the positional relationship between the paired head and the recording track, and FIG. 4 is a diagram of changes in signals of each part of the same embodiment when the paired head changes its position in the recording track width direction. , FIG. 5 is an explanatory diagram showing an example of the concept of a signal division method when using a pair head. 1. River... Pair Hera)", 101, 102...
Magnetic head, 103, 104, river...head gap,
7゜8...Detection l flow path, 9...Differential amplifier circuit. Name of agent: Patent attorney Toshi Nakao and one other person No Ya Ahead? --- Head scan 7 addition 3 --- λ mark stage 4 --- 1 Hill tape p - Takekata simple tot, t θ2 --- Door air head l θ 3.1011 --- Hesodogi, -, pu m'1 Figure 3 Figure 4 Figure 5 S-C Se#C flower name- -mouth-

Claims (1)

[Claims] Two magnetic heads with different azimuth angles simultaneously scan two adjacent recording tracks, and when reproducing information signals, each magnetic head is made wider than the track width of each recording track. , by detecting the amplitude difference between the reproduced signals from each of the magnetic heads,
A tracking error detection device characterized by detecting a tracking error.