JPH01220214A - Tracking error signal generation circuit - Google Patents

Abstract

PURPOSE:To automatically set an on-track position by setting the reference value of an on-track state at the optimum state automatically by a reference value generating means. CONSTITUTION:A time difference detection circuit 109 discriminates which horizontal synchronizing signal 107 or 108 is reproduced first. A circuit 114 is a maximum value detection circuit, and outputs a signal 115 whose polarity changes when a signal reproduced by a head 1011 becomes maximum. A reference value generation circuit 112 generates the reference value by using the value of a time differential signal 110 at a time when the polarity of the signal 115 changes. A track deviation arithmetic circuit 111 outputs a tracking error signal 116 which drives an electric-mechanical conversion element so as to minimize a difference between the time differential signal 110 supplied from the time difference detection circuit 109 and the reference value supplied from the reference value generation circuit 112, and controls the feed phase of a tape. In such a way, it is possible to prevent the deviation of tracking from being generated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is used in magnetic recording/reproducing devices, etc.
Creating a dragging error signal to obtain a tracking error signal by using the difference in reproduction time of each reproduction signal that is reproduced by simultaneously scanning a magnetic medium with at least two heads having different azimuth angles mounted on a mechanical transducer element. It is related to circuits.

Conventional technology recording and reproducing equipment, for example, magnetic recording and reproducing apparatus (hereinafter simply referred to as V
When reproducing an information signal recorded on a recording track, tracking control is required so that the reproduction head on-tracks and scans the recording track for reproduction.

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

However, this method has drawbacks such as requiring a dedicated control track and not being able to obtain a tracking error signal over the entire recording track.

Another method that has been put into practical use is to record a pilot signal for tracking control on the recording track, and when reproducing, the reproduction level of each pilot signal reproduced from both adjacent tracks of the main track scanned by the head for reproduction is adjusted. There is a method to compare and obtain a tracking error signal. In this method, since a tracking error signal can be obtained over the entire recording track, the reproducing 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 can follow track bending. However, this method has the disadvantage that since it is necessary to superimpose the pilot signal on the information signal and record it, the band of the information signal is reduced only outside the band of the pilot signal, and the S/N of the information signal deteriorates accordingly. .

In order to solve these drawbacks, a method has been proposed in which a tracking error signal is obtained over the entire recording track without using a pilot signal.

This method is disclosed in Japanese Unexamined Patent Publication No. 55-150129, and utilizes the relationship between the track slippage in azimuth recording and the closing difference during reproduction of the reproduced signal. Since the present invention relates to this method, the basic idea of this method will be explained below.

FIG. 19 shows magnetization trajectories recorded by two heads with different azimuth angles. In the figure, 1901 is a magnetic tape, which is transported in the direction of arrow 1902. 1903 and 1904 are heads with different azimuth angles,
The magnetic tape 1901 is simultaneously scanned in the direction of arrow 1905. Such a head, that is, a head that scans simultaneously and has mutually different azimuth angles, will hereinafter be referred to as a bare head. 1906 and 1907 indicate head gaps in each head.

A1, A2, A3, . . . are magnetization trajectories recorded with a head having the same azimuth angle as the A head shown in 1903, and B1, B2, B3, . These are magnetization trajectories recorded by heads with the same azimuth angle. 81. Track pair of B1 and A2, B2
track pairs may be recorded with the same pair of heads,
Further, other bare heads may also be recorded. This relationship is determined by the rotational speed of the rotary cylinder containing the rotary head and the number of built-in paired heads, and can be freely determined at the time of device design. The signal recorded on each magnetization trajectory, for example, the magnetization pattern such as a horizontal synchronization signal, is 190
8 and 1909, recording is performed at an angle oblique to the longitudinal direction of the track, that is, at an azimuth angle.

The method of recording and reproducing information signals using paired heads is effective when the frequency band of the information signals to be handled is large. This is because when recording an information signal at a constant head scanning speed, the higher the recording frequency of the information signal, the narrower the recording wavelength recorded on the magnetic tape becomes, and the shorter it becomes, the more difficult practical recording and reproduction becomes. This is because if a paired head is 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. 20 is a diagram showing the concept of dividing the information signal to be recorded into two types of signals. In the figure, 20a indicates the original signal to be recorded, and 20b and 20c indicate signals obtained by dividing the original signal, that is, actual recording signals supplied to the paired heads. The original signals 2001 and 2002 are temporally divided, for example, as shown in the figure, and are divided into 2003 and 2002.
The data is expanded and divided in time as shown in 004. In other words, the frequency band can be lowered by the amount of temporal expansion. In the same figure, 2005.2006.200
7 and the like are timing signals, for example, horizontal synchronization signals. Note that the method of dividing the original signal is not limited to the method of dividing in time; for example, the method of dividing in terms of frequency,
There is a method of dividing according to the type of signal, such as a luminance signal or a color signal. In any case, when recording signals with a wide band, the method of using paired heads is practically effective and is a necessary condition.

FIGS. 17a to 17c show three positional relationships between the recording magnetization locus and the reproducing scanning head. In the figure, 1701, 1702, and 1703 indicated by broken lines are hair heads, each consisting of an A head and a B head.

Each paired head scans in the direction of arrow 1704. A1, B
1 is the magnetization trajectory recorded by the paired head, 1705
The signals indicated by 1710 indicate the recording position of the horizontal synchronization signal.

The position of the paired head with respect to the recorded magnetization trajectory is shown in Figure 17a.
17, it is on track in FIG. 17, and it is shifted to the right in FIG. 17C. When a recording track is read back and scanned with a head having such a relative positional relationship, even signals recorded at the same time are played back at different times. For example, in FIG. 17a, the time at which horizontal synchronization signal 1705 is reproduced by head A is slower than the time at which horizontal synchronization signal 1706 is reproduced by head B. In FIG. 17, the reproduction time of both horizontal synchronization signals is equal, and in FIG. It will be faster than Therefore, A
By checking the time difference between the horizontal synchronization signals reproduced by heads B and B, track deviation can be determined.

Note that the signal for checking the time difference is not limited to the horizontal synchronization signal, and may be any other specific signal; however, in the following description, the horizontal synchronization signal will be explained as a specific signal.

FIG. 18 ζ is a diagram showing the relationship between track slippage and the closed difference during reproduction of each horizontal open Y bar signal reproduced by multiple heads A and B. The horizontal axis shows the track deviation, and the position indicated by zero is the on-track position.

The deviations indicated by right and left correspond to the direction of deviation of the head on the plane of the paper with respect to the recording track shown in FIG. The vertical axis shows the reproduction time difference of the horizontal synchronizing signal reproduced by the A and B multiple heads, and the on-track position is when the time difference is zero. Further, the time when the horizontal synchronization signal reproduced by the A head is slower than that by the B head is defined as the child direction.

At this time, the relationship between the track deviation and the time difference of the reproduced signal is 1
801. As is clear from FIG. 18, if the tracking control circuit is configured so that the time difference shown on the vertical axis is zero, the reproduction head will always be on-track and perform reproduction scanning on the recording track.

Problems to be Solved by the Invention As mentioned above, the method of performing tracking control by detecting the time difference between the signals reproduced by the pair of heads cannot be performed when the center positions of the helad gaps of the A and B heads are exactly the same. This is effective, but if they do not match, track deviation will occur. This will be explained next.

FIGS. 16A to 16C are diagrams showing how the three types of heads A and B are installed. In the same figure, 160L
1603.1605 indicates A head, 1602.16
04.1606 indicates B head.

The scanning direction of each head is arrow 1607, l608.160
This is the direction indicated by 9. Reference numerals 1612, 1613, and 1614 are members for installing each head, which are movable members made of piezoelectric elements or the like. The heads A and B are installed at different positions in a direction perpendicular to the scanning direction. The gap between each head is indicated by a diagonally drawn solid line within each head, as shown by 161O11611.

FIG. 16a shows a normal installation, with the center points 1615 and 1616 of the gaps of each head lying on a line 1617 perpendicular to the scanning direction of the heads. In other words, there is no shift in the scanning direction. The magnetization trajectory recorded by such a head is recorded in a line of signals at the same time in a direction perpendicular to the longitudinal direction of the recording track.

FIG. 16 shows a state in which the heads are installed irregularly, with the center point of the gap between each head being deviated by an amount indicated by 1618 with respect to the scanning direction. In the magnetization trajectory recorded by such a head, signals at the same time are recorded with a deviation of an amount indicated by 1618 in the longitudinal direction of the recording track.

FIG. 16C shows another method of mounting the head. In the figure, the center points of the head gaps between heads 1605 and 1606 are set apart by an interval 1618 corresponding to the recording wavelength of the horizontal synchronizing signal, and the head height difference caused by shifting the heads Amount 1
619 is corrected by a height correction member 1620. It is well known that even when such a head is used, the recording positions of the horizontal synchronizing signals can be aligned in the longitudinal direction of the recording track. But in this case too, the interval 1618
If the wavelength is not set exactly to the wavelength of the horizontal synchronizing signal or an integral multiple thereof, the same condition as shown in FIG. 16 will occur.

Figure 14 is a diagram showing the relationship between the recording magnetization trajectory and the reproducing head when a magnetization trajectory recorded by a pair of heads with the heads mounted out of position is reproduced by another pair of heads with the heads mounted out of alignment. be. 1401 and 1402 are heads A and B, and 1403 and 1404 indicate recording positions of horizontal synchronization signals.

The figure shows a state in which the paired heads are on-track and scanning on the recording track. At this time, the difference in the reproduction time of each horizontal synchronization signal reproduced by the A and D heads is:
The time corresponds to the difference in distance shown by 1405 and 1406. In other words, even when on-track, the playback signal,
There will be a time difference.

FIG. 15 shows the relationship between track slippage and the time difference between reproduced signals, and the vertical and horizontal axes have the same meanings as in FIG. 18. In the same figure, 1801 is the same characteristic as the characteristic shown in FIG. That is, the on-track position is when the time difference is zero.

On the other hand, the characteristic indicated by 1501 is the characteristic when the relationship between the head and the recording magnetization locus is as shown in FIG. That is, the time difference does not become zero at the on-track position. If control is performed so that the time difference becomes zero at this time, the control system will be stabilized at the track position indicated by 15o2.

The mounting accuracy of each head, A and B, is determined by the mechanical precision when assembling the head, and variations will always occur.

Therefore, the relationship between the signal recording position and the playback pair head is as follows:
It can be said that the relationship shown in FIG. 14 is general. Moreover, since the distance WlrfII between 1405 and 1406 shown in FIG. 14 differs depending on each deck, unless this problem is solved, the method shown in Japanese Patent Publication No. 150129/1983 cannot be used practically.

The present invention provides tracking that can automatically set the on-track position even if the relationship between the recording position of the signal on the recording track and each gap of the reproduction pair head is as shown in FIG. The purpose of this invention is to provide an error signal generation circuit.

Means for Solving the Problems The present invention solves the above-mentioned problems by simultaneously scanning a magnetic tape with at least two playback heads having different azimuth angles mounted on an electro-mechanical conversion element. means for obtaining a closed difference during reproduction of a specific signal included in the reproduced signal; reference value creation means for creating a reference value for tracking control; and detecting a maximum value of at least one of the reproduction signals. maximum value detection means; tracking error calculation means for outputting a tracking error signal for driving at least the electro-mechanical conversion element so that the difference between the closed difference during reproduction and the reference value is minimized; It consists of a phase pull-in detection means for detecting that the phase relationship between the head and the scanning track is within a specific range.

Alternatively, a timer means outputs a start signal when a certain time has elapsed from the time when the playback operation started.

With the above-described configuration, the present invention automatically sets the reference value for the on-track state to the optimum state by the reference value creation means, so that there is no need to worry about the deviation of the recording position of a specific signal on the recording track or the installation of the reproducing head. Even if there are variations in position, the reproducing head can always be on-track on the recording track and perform reproducing scanning.

EXAMPLE Before explaining the present invention in detail, the basic idea of the present invention will be explained.

FIG. 10 shows a configuration diagram of the rotating cylinder.

Moreover, FIG. 11 shows the recorded magnetization locus recorded by the cylinder shown in FIG. 1O. Rotating cylinder 1001
The first pair of recording heads RAI (1003) and RB
I (1004) and the second recording pair head RA2 (1
005)・PH2 (1006) are installed at positions 180 degrees opposite each other, and the first reproduction pair head PA
3 (1009) and PH1 (1010) and the second playback pair head PA4 (1011) and PH4 (1012) are 1
They are installed at 80 degrees opposite positions, and the arrow 100
Rotate in two directions.

The magnetic tape 1101 shown in FIG.
001 and runs in the direction of arrow 1102, and the recording head/reproducing head scans the magnetic tape in the direction of arrow 1103. When recording, recording head RA
A recording track ALA3 . . . is formed by the recording head I, and recording tracks B1, B3 . . . are formed by the recording head RB1. Further, recording tracks A2, A4, . . . are formed by the recording head RA2, and recording tracks B2, B4, . . . are formed by the recording head RB2.

The recording heads RAI and RA2 have the same azimuth, and the horizontal synchronization signal is 11 for the recording tracks A1 and A2.
It has a slope shown as 04.1106.

Similarly, the recording heads RBI and PH2 have the same azimuth, and the horizontal synchronization signal has an inclination of 1105 and 1107 with respect to the recording track B1-82.

Playback pair head PA3/PA3 is electrical-mechanical conversion! "It is installed in the child 1007, and the playback pair head PA4・P
H4 is mounted on the electro-mechanical conversion element 1008.

A dedicated control track 1112 is provided in the tape longitudinal direction of the magnetic tape 1101, and during recording, a control signal 1114 is recorded every four tracks by a control head 1113, and during playback, a playback control signal reproduced by the control head 1113 is recorded. The phase of the capstan motor is controlled so that the phase relationship between the reference signal and the reference signal is constant. During playback, when the phase control of the capstan motor is applied, the playback pair head PA3/PH1 moves to the recording track pair (AI-B
l), (A3/B3), and the playback pair head PA
4・PB4 is the recording track pair (A2・B2), (A4
・Scan B4).

Here, as explained in FIG. 14, the playback pair head P
In order for A3 and PA4 to scan the recording tracks A1 and Bl on-track, it is necessary to understand the relationship between the magnetization trajectories 1104 and 1105 of the horizontal synchronization signal and the helad gaps 1108 and 1109 at the time of on-track.

Also, the playback pair heads PA4 and PB4 are on the recording track A.
2. In order to scan B2 on-track, the magnetization locus 1106 of the horizontal synchronization signal at the time of on-track is
107 and the Herad gap 1110-1111 must be understood.

Hereinafter, a method of determining the relationship between the magnetization locus of the horizontal synchronization signal and the herad gap during on-track will be explained.

FIG. 12 is a diagram showing the relationship between the recording magnetization trajectory and the head scanning trajectory of the reproducing head PA4, and FIG.
FIG. 2 is a diagram showing changes in the output of the reproduced signal during each head scan shown in FIG. 2(C).

In FIG. 12, A1, A3, . . . are recording heads R.
These are magnetization trajectories recorded by AI, A2, A4...
is the magnetization locus recorded by the recording head RA2. B1
, B3, . . . are magnetization trajectories recorded by the recording head RBI, and B2, B4, . . . are magnetization trajectories recorded by the recording head RB2.

FIGS. 12(a), 12(b), and 12(c) show the relationship between the recording magnetization trajectory and the head scanning trajectory of the reproducing head PA4 from the tape stop state to the normal reproduction state.

FIG. 12(a) shows the tape stopped state, and FIG. 12(b)
) shows a state where the capstan motor is speed controlled but no phase control is applied, and FIG. 12(C) shows a state where the capstan motor is speed controlled and phase controlled.

As shown in FIG. 12(a), when the tape is stopped, the scanning locus of the playback head PA4 becomes as shown by 1201, and the recording tracks to be scanned A2. Or, it is not always necessary to scan A4 paper. Similarly, as shown in FIG. 12(b), even when the capstan motor is under only speed control and no phase control, the scanning trajectory of the playback head PA4 is 12.
02 and the recording track to be scanned is A2.
Or, it is not always necessary to scan A4 paper. Figure 12 (C
), it is not until the speed and phase control of the capstan motor is applied that the reproducing head P is activated as shown at 1206.
A4 scans the recording track A2 to be scanned.

Here, when the tape transitions from the stopped state to the playback state,
A driving voltage is applied to the electro-mechanical transducer 1008, and the electro-mechanical transducer is displaced so that the head scanning trajectory becomes 1203 with respect to the head scanning trajectory 1206, so that the reproducing head PA4 scans across the recording track A2. In this case, if the phase relationship between the playback control signal and the reference signal is within a certain range before the phase control of the capstan motor is applied, the scanning locus of the playback head PA4 will be as shown at 1204 or 1205. become.

FIG. 13 shows the head scanning trajectory 1203 in FIG. 12(C).
．． Scanning time from one end to the other end in the longitudinal direction of recording track A2 corresponding to 1204.1205, 13
FIG. 2 is a diagram showing changes in the output of the reproduced signal within 01.

1303 is the output change during head scanning of 1203.
05 is the output change during head scanning of 1205, 1307
indicates the output change during head scanning in 1204. The time at which the maximum value 1304, 1306 or 1308 of the reproduced signal is obtained is 1207 in the head scanning trajectory 1203.
In the head scanning trajectory I2O3, it is the time for the head to scan the position indicated by 120 days, and in the head scanning trajectory 1204, it corresponds to the time for the head to scan the position indicated by 1209. do. That is, it corresponds to the time when the center point of the Herad gap of the reproducing head PA4 is on track with the magnetization locus A2. Therefore, it is sufficient to check the time difference between the reproduction signals at the time when the output level of the reproduction signal reaches its maximum value and use this time difference as the reference value for the on-track position. This reference value may be created each time the tape is switched from stopping to the playback state, that is, each time the stop mode is changed to the playback mode.

Next, a first embodiment of the present invention will be described.

FIG. 6 is a diagram showing signal processing during recording.

In the figure, a video signal to be recorded is manually inputted from a terminal 601. The circuit 602 is a recording signal processing circuit, and as already explained using FIG. 20, performs processing such as converting the frequency band of the original signal into a recordable frequency band.

603 and 604 are recording amplifiers, and the recording head RA
2 (1005) and recording head RB2 (1006)
supply the recording signal to.

FIG. 1 is a block diagram showing a first embodiment of the present invention, and the details of the time difference detection circuit 109, reference value creation circuit 112, maximum value detection circuit 114, and servo lock detection circuit 126 shown in the same figure are explained below. will be described later.

In Fig. 1, playback pair head PA4 (1011)/P
H1 (1012) is mounted on the electro-mechanical conversion element 1008. 103 and 104 are regenerative amplifiers.

Reference numeral 105 denotes a reproduced signal processing circuit, which converts the signals reproduced from each head into the same format as the original signal to produce a reproduced video signal, and outputs the signal from a terminal 106. Further, the reproduction signal processing circuit 105 outputs specific signals reproduced from each head, that is, horizontal synchronization signals 107 and 108. The time difference detection circuit 109 is a circuit that detects the closing difference during reproduction of each of these horizontal synchronization signals. A signal 110 corresponding to this time difference is sent to a track deviation calculation circuit 111.
and is supplied to the reference value creation circuit 112. The time difference detection circuit 109 outputs a time difference signal and also
4. It also outputs a polarity determination signal 113 for determining which horizontal synchronization signal is reproduced earlier among the horizontal synchronization signals reproduced from each head. The circuit 114 is a maximum value detection circuit, and outputs a signal 115 whose polarity changes when the signal reproduced by the PA4 head 1011 reaches the maximum. The reference value creation circuit 112 creates a reference value using the value of the time difference signal 110 at the time when the polarity of the signal 115 changes.

The track deviation calculation circuit 111 receives the time difference signal 110 supplied from the time difference detection circuit 109 and the reference value creation circuit 11.
A tracking error signal 116 is output that drives the electro-mechanical conversion element so that the difference from the reference value supplied from 2 is minimized.

The tracking error signal 116 is supplied to a capstan motor control circuit 117 and also to a piezoelectric element drive circuit 119 via an adder circuit 118. In the capstan motor control circuit 117, tracking error signal 1
16 to control the tape feeding phase. The piezoelectric element drive circuit 119 uses the tracking error signal 116 to drive the playback pair heads PA4 (1011) and PH1 (101).
2) to perform track bending follow-up control. The circuit 120 is a system control circuit, and outputs various mode command signals in response to the key input signal 121. The circuit 120 is supplied with not only the key input signal but also a PC signal indicating the rotational phase of the rotary head from a terminal 122.

A gate signal 123 outputted from the system control circuit 120 indicates that one head is
High (
This is a signal that is at a high (High) level. The servo lock detection circuit 126 detects the phase relationship between the reference signal 127 output from the capstan motor control circuit 117 and the servo comparison signal 128 such as a reproduction control signal, and detects if the phase relationship between the two signals is within a certain range. Servo lock detection signal 1
29 is considered a high level. Only while the gate signal 123 is at a high level, the maximum value detection circuit 114 operates and the switch 124 is closed. Circuit 125 is a preset waveform creation circuit. This preset waveform creation circuit 1
As already explained using FIGS. 12 and 13, 25 is a circuit for creating a sawtooth wave signal for driving the piezoelectric element so that the reproducing head traverses the recording track. Further, the reference value generation circuit 112 operates only while the servo lock detection signal 129 is at a high level.

FIG. 4 is a detailed block diagram of the maximum value detection circuit 114 shown in FIG. 1, and FIG. 5 shows waveforms at various parts in FIG. Identical symbols in both figures indicate the same thing.

In FIG. 21, a reproduced signal 5b is input manually from a terminal 401. In the reproduced signal 5b shown in FIG. 5, the head scans across the recording magnetization locus in the width direction during the period indicated by 501, and the head scans on the recording track in the other periods. This figure shows a reproduction signal obtained during reproduction scanning. For such head scanning, it is sufficient to move the head using an electro-mechanical transducer such as a piezoelectric element only during 1jII indicated by 501 in the normal reproduction mode. The reproduced signal 5b is detected and rectified by a detection rectifier circuit 402, and becomes a signal shown by a broken line 502 in FIG. 5C.

The circuit 403 is a peak bold circuit that holds the high value of the signal 502, and its output signal is a signal indicated by 503. From the terminal 407, gate No. 13 5a is manually operated. This gate signal is the output signal 123 of the system control circuit 120 shown in FIG. 1, and is a signal that becomes high level only during the period when the head scans one track at any time in the reproduction mode. The peak hold circuit 403 operates while the gate signal is at a high level, and the output signal is at a low level while the gate signal is at a low level. A circuit 404 is a level comparison circuit that compares the level of the output signal 502 of the detection rectification circuit 402 and the level of the output signal 503 of the peak hold circuit 403. The output signal of the comparator circuit 404 is shown in FIG.
As shown in FIG. 3, when the level of the output signal of the peak hold circuit 403 is higher than the output signal level of the detection rectifier circuit 402, a high level signal is output. The switch circuit 405 takes out the signal 5d when the gate signal 5a is at a high level, and is connected to the ground side during a period at a low level. A timing signal 5d for creating a reference value, which will be described later, is taken out to the terminal 406.

FIG. 2 is a detailed block diagram of the time difference detection circuit 109 and reference value creation circuit 112 shown in FIG. 1, and a diagram showing the track deviation calculation circuit 111, and FIG. shows the signal. The same symbols in FIG. 1, FIG. 2, and FIG. 3 indicate the same thing.

In FIG. 2, a horizontal synchronizing signal 3a included in a signal reproduced by a PA4 head is inputted from a terminal 201, and a horizontal synchronizing signal 3c included in a signal reproduced by a PB4 head is inputted from a terminal 202. IIJ 203 is a delay circuit that is triggered by the rising edge of the signal 3a and outputs a high-level pulse signal 3b for a period of 3010 shown in FIG. Circuit 204 is a reset-set flip-flop (R-5-FF) circuit that is set on the rising edge of signal 3c and reset on the falling edge of signal 3b. R-S-FF circuit 2
The output signal 3d of 04 and the output signal 3b of the delay circuit 203 are input to an exclusive OR (EX-OR) circuit, and the output signal 3d of the delay circuit 203 is
get e. The high level period 302 of the signal 3e indicates the time between each horizontal synchronizing signal, so if the A and B heads are installed in a normal state, this time will indicate a track misalignment. Become. The circuit 206 is a counter circuit, and starts counting at the rising edge of the signal 3e, and resets the count value at the falling edge of the signal 3b. A clock for counting is manually inputted from the terminal 207. Circuit 208 is a latch circuit, and latches the count value of counter circuit 206 at the falling edge of signal 3e.

Therefore, the latch circuit 208 latches a value corresponding to the time difference between the horizontal synchronization signals.

Signal 3[ shown in FIG. 3 is a diagram showing a state when signal 3C is at a position temporally ahead of signal 3a,
At this time, the output 3d of the R-5-FF circuit 204 is 3g
The waveform shown is shown below. Also, EX-OR circuit 2 at this time
The output of 05 has the waveform shown in 3h. Also at this time, a value corresponding to the time indicated by 303 is stored in the latch circuit 208.

Signal 3a is delayed by delay circuit 213 to obtain an output signal designated 3I. The circuit 216 is a D flip-flop (
D-FF) circuit, and the human power level of signal 3e is
Latch at the rising edge of 1. Therefore, if the horizontal synchronization signal reproduced by the PB4 head lags behind the horizontal synchronization signal 3a reproduced by the PA4 head as shown in 3c, the output signal of the D-FF circuit 216 will be at a high level. . Conversely, if the signal progresses as indicated by signal 3f, the output signal of circuit 216 becomes low level. Therefore, circuit 2
The output signal 217 of No. 16 is a signal indicating whether the horizontal synchronization signal reproduced from the B head is delayed or ahead of the horizontal synchronization signal reproduced from the A head, that is, the polarity of the tracking error signal ( This is a signal indicating whether the position is shifted to the right or left from the on-track position.

The output of the latch circuit 208 shown in FIG. 2 is input to another latch circuit 210. One input terminal 220 of the AND circuit 218 is supplied with the pulse signal 5d that rises at a time near the maximum value of the reproduced output signal, as already explained in FIG. 5, and the other input terminal 219 is supplied with the servo signal. The lock detection signal is manually generated. The latch circuit 1210 latches the value of the latch circuit 208 when the phase relationship between the magnetic tape and the reference signal is within a certain range and at the timing of the rising edge of the signal 5d. That is, the latch circuit 21
0, the time difference between each horizontal synchronization signal at the time of on-track is stored as a reference value for tracking control.

The value of the output signal 110 of the latch circuit 208 indicating the closing difference during reproduction of each horizontal synchronizing signal at any time and the reference +1ff
215 is fU in the track deviation calculation circuit 111.
Alternatively, the difference value is determined taking into account the polarity of the signal 113. Therefore, a tracking error signal is taken out from the terminal 209, taking into consideration the mounting condition of the head.

FIG. 7 shows a configuration diagram of the servo lock detection circuit 126. FIG. 8 shows the servo lock detection circuit 126 shown in FIG.
Represents the signal waveform of each part inside. A reference signal is input to the terminal 701, and its waveform is shown in 8-a. Further, a reproduction control signal, which is a phase comparison signal for the capstan motor during reproduction, is input to the terminal 702, and its waveform is shown in 8-d. When the capstan motor is under phase control, the phase relationship between the reference signal and the reproduction control signal is as indicated by 802. The reference signal is input manually to the monostable multivibrator 703, and the insect-stable multivibrator 703 outputs a signal shown in 8b. Further, the output of the monostable multivibrator 703 is input to the monostable multivibrator 704, and the monostable multivibrator 704 outputs a signal shown in 8c. 705 is a D-flip-flop, the output of the monostable multivibrator 704 becomes the D input, and the reproduction control signal becomes the C input.

Since the D-flip-flop 705 outputs a signal level of 0 at the rising edge of the C signal, if the rising edge of the playback control signal is in the 801 range, a high level signal is obtained at the output terminal 706, and therefore the output If a high level voltage is obtained at the terminal 706, it can be detected that the phase relationship between the reference signal and the reproduction control signal is within the set range.

In this way, the reference value of the tracking error signal obtained by the reproducing bare heads PA4 and PB4 reproducing the horizontal synchronization signals recorded by the recording bare heads RA2 and RB2 can be determined.

It is clear that similarly, the reproducing bare heads PA3 and PB3 can obtain tracking error signals obtained by reproducing the horizontal synchronization signals recorded by the recording bare heads RAI and RBI.

Further, in the first embodiment of the present invention, a recording head and a reproducing head are provided separately, but these heads may be the same.

FIG. 9 shows a block diagram of a second embodiment of the invention.

The difference between the second embodiment and the first embodiment of the present invention is that a timer circuit 90 is used instead of the servo lock detection circuit.
1 is used.

The operation of timer circuit 901 will be explained below. A mode switching signal 902 is inputted to the timer circuit 901 from the system control circuit 120. The mode switching signal is a signal that is at a low level in modes other than the normal driving mode, and is at a high level in the reproduction mode.

When the timer circuit 901 receives a high-level mode switching signal 902 manually, it outputs a reference value creation circuit control signal 903 that changes from low level to high level after a certain period of time T1. The reference value creation circuit control signal 903 is the first
It has the same function as servo lock detection No. 13 in the embodiment, and when the level of this signal is high, the reference value creation circuit 112 operates and creates a reference value for tracking error. Here, it is preferable that the time TI is set longer than the time required for phase control of the capstan motor after the mode changes from a mode other than the normal running mode to the regeneration mode.

In this way, the reference value of the tracking error signal that can be obtained by reproducing the horizontal synchronization signal recorded by the recording pair heads RA2 and RB2 by the reproduction pair heads PA4 and PB4 can be determined.

It is clear that in the same way, the reproduction pair heads PA3 and PB3 can obtain the tracking error signal obtained by reproducing the horizontal synchronization signal recorded by the recording pair heads RAI-RBI.

As mentioned above, the specific signals reproduced from each recording track are
Although the explanation has been made using the Irrigation In signal in the signal, the specific signal in the present invention is not limited to the horizontal synchronization signal. For example, in digital recording of audio and data, address data reproduced block by block may be used as well. can perform the following actions.

Effects of the Invention As is clear from the above explanation, according to the present invention, the on-track state is known by detecting the maximum value of the reproduced output signal, and the on-track state is known by detecting the maximum value of the reproduced output signal. In order to calculate a reference value for calculating a tracking error signal, installing a pair of heads has the effect of preventing tracking deviations due to errors.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a tracking error signal generation circuit according to the first embodiment of the present invention, FIG. 2 is a detailed block diagram of a time difference detection circuit and a reference value generation circuit, and FIG.
Figure 4 is a detailed block diagram of the maximum value detection circuit; Figure 5 is a waveform diagram showing the waveforms of each part in Figure 4; Figure 6 is a block diagram showing the recording circuit. Figure, 7th
The figure is a detailed block diagram of the servo lock detection circuit, No. 8.
The figure is a waveform diagram showing the waveforms of each part of Fig. 7, Fig. 9 is a block diagram showing the second embodiment of the present invention, Fig. 10 is a configuration diagram of the rotating cylinder, and Fig. 11 is the recording magnetization trajectory and reproduction. 12 is a plan view showing the relationship between the recording magnetization trajectory and the reproducing head scanning trajectory in the tape running mode; FIG. 13 is a plan view showing the relationship between the recording head scanning trajectory and the reproducing head scanning trajectory; A characteristic diagram showing the output change of the reproduced signal in the head scanning trajectory. Figure 14 shows the magnetization trajectory recorded using the irregularly mounted head and the relative position with the other irregularly mounted head. A plan view showing the relationship, FIG. 15 is a characteristic diagram showing changes in the tracking error signal when a head is used with an irregularly installed head, and FIG. 16 is a plan view showing the various head installation conditions. Fig. 17 is a plan view showing the relative positional relationship between the recording magnetization locus and the reproducing head, Fig. 18 is a characteristic diagram showing changes in the tracking error signal under normal installation conditions, and Fig. 19 is a graph showing the magnetization locus and the relative positional relationship between the read head and the reproducing head. FIG. 20 is a plan view showing the relationship with the paired head, and a characteristic diagram showing the concept of the signal division method when using the paired head. 105... Reproduction signal processing circuit, 109... Time difference detection circuit, 111... Track shift calculation circuit, 112...
...Reference value creation circuit, 114...Maximum value detection circuit, 1
17... Capstan motor control circuit, 119...
Piezoelectric element drive circuit, 120... System control circuit, 125... Preset waveform creation circuit, 126.
...Servo lock detection circuit. Name of agent Patent attorney Toshio Nakao 1 person Figure 3; (L) 1 Figure 5 <ch -m-''-]-11 Figure 7 Figure 10 Figure 11\ 1.4□ ″' Figure 15 Track deviation Figure 16 ((IJ
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(C) Fig. 18 Left truck - O□ Right truck? tl @Figure 19Figure 20

Claims (2)

[Claims] (1) In an apparatus for reproducing at least two parallel recording tracks simultaneously recorded on a magnetic recording medium using magnetic heads having different azimuth angles, at least two parallel recording tracks having different azimuth angles mounted on an electro-mechanical transducer are used. means for obtaining a playback time difference between specific signals contained in each playback signal reproduced by simultaneously scanning the magnetic tape by a playback head; a reference value creation means for creating a reference value for tracking control; , maximum value detection means for detecting a maximum value of at least one reproduction signal, and a tracking error signal for driving at least the electro-mechanical conversion element so that the difference between the reproduction time difference and the reference value is minimized. comprising a tracking error calculation means for outputting, and a phase pull-in detection means for detecting that the phase relationship between the reproducing head and the scanning track is within a specific range,
After starting a reproducing operation, when the phase entrainment detection means detects that the phase relationship between the reproducing head and the scanning track is within a specific range, the electric current is activated so that the reproducing head crosses the recording track. - the reference value creation means operates to displace the mechanical transducer element and set the reproduction time difference at the time when the maximum value of the reproduction signal is detected by the maximum value detection means as a reference value for subsequent tracking control; Features a tracking error signal generation circuit. (2) In an apparatus for reproducing at least two parallel recording tracks simultaneously recorded on a magnetic recording medium using magnetic heads having different azimuth angles, at least two parallel recording tracks having different azimuth angles mounted on an electro-mechanical transducer are used. means for obtaining a playback time difference between specific signals contained in each playback signal reproduced by simultaneously scanning the magnetic tape by a playback head; a reference value creation means for creating a reference value for tracking control; , maximum value detection means for detecting the maximum value of at least one reproduction signal, and a tracking error for driving at least the electro-mechanical conversion element so that the difference between the closed difference during reproduction and the reference value is minimized. It consists of a tracking error calculation means that outputs a signal, and a timer means that outputs a start signal when a certain time has elapsed from the time when the playback operation started, and after the start of the playback operation, the start signal is output from the timer means. When the reproduction signal is output, the electro-mechanical transducer is displaced so that the reproduction head traverses the recording track, and the reproduction time difference at the time when the maximum value of the reproduction signal is detected by the maximum value detection means is determined from that point onwards. A tracking error signal generation circuit characterized in that the reference value generation means operates to use the reference value as a reference value for tracking control.