JPH02118913A - Generating device for tracking error signal - Google Patents

Abstract

PURPOSE:To simply recognize a mount error by providing a preset value setting means correcting the mount error of each head forming a pair head. CONSTITUTION:Magnetic heads A1, A2 and B1, B2 are heads in pairs. Circuits 201 - 204 are head amplifier circuits, which amplify signals reproduced from the magnetic heads A1 - B2. Analog switches 205, 206 select and extract alternately a signal reproduced by the heads A1 or A2 and B1 or B2. Each extracted signal is fed to a reproducing signal processing circuit 207, in which the signal is demodulated into a normal video signal and outputted to a terminal 208. Only a special signal is separately extracted by a specific signal separation circuit 210 from the output signal of the analog switches 205, 206, the signal is supplied to a tracking error signal generating circuit 211, a reproduced time difference of the specific signal is detected and the result is outputted at a terminal 212 as a tracking error.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a tracking error signal generating device for a magnetic recording/reproducing device.

BACKGROUND OF THE INVENTION In recent years, recording and reproducing technology for magnetic recording and reproducing devices (hereinafter simply referred to as VTR) has been developed using conventional VTRs for recording and reproducing analog signals.
From TRs, digital VTRs have evolved into digital VTRs, which directly record and reproduce digital signals on magnetic tape.

Since digital signals have a larger amount of information than analog signals, it is not possible to record one field of video signals as one recording track like in an analog VTR.
It is normal to record data divided into several tracks.

FIG. 10 shows the magnetization locus of the digital signal.

In the figure, 1001 is a magnetic tape, and arrow 100
It is transported in two directions. 1003 and 1004 are heads having different azimuth angles, and a pair of these heads will hereinafter be referred to as a pair of heads. Pair head is arrow 10
Scan in the 05 direction.

A11. A21. Bit, B21, . . . are recording trunks recorded by each pair head. The pair head is 1003. Another bare head (not shown) is placed at a position 180 degrees νj 1006.1007 indicates the recording position of a specific signal, and ■Multiple specific signals are recorded in the trunk.For example, the specific signal is a horizontal synchronization signal in an analog VTR, and each signal in a digital VTR. This is a /link signal added to each block.

In a VTR, recording tracks should originally be recorded in a straight line on a magnetic tape, but in reality they are recorded in a curved form peculiar to the tape due to variations in mechanical precision. For this reason, when a tape recorded on one deck is played back on another deck, the head does not accurately scan the recording track for playback, and the playback output may deteriorate accordingly. In order to solve this problem, there is a method to obtain track curvature information over the entire recording track, and to perform tracking by varying the playback angle in the width direction of the recording track using an electromechanical transducer composed of a piezoelectric element, etc. It has been known.

One method of obtaining a tracking error signal over the entire recording track is to use a reproduction time difference between specific signals. Since the present invention relates to this method, a method for obtaining a tracking error signal using reproduction time differences will be described first.

FIG. 8 is a diagram showing the relative positional relationship between the recording track and the reproduction bare head. In the figure, A11 and A21 are tracks recorded by a pair of heads, 809 and 810.
．． 811 is a pair head. FIG. 8 shows three types of head scanning positions. At a position 810 where the paired head scans the recording track on-track, each head 805 and 806 reproduces each specific signal 801 and 802.
have the same playing time. However, when the head scans the position indicated by 809, the head 804 uses the specific signal 802.
The specific signal 801 is played back by the head 803.
This is faster than the time it takes to play. Further, when the paired head is at the scanning position indicated by 811, the time for reproducing the specific signal 802 by the head 808 is slower than the time for reproducing the specific signal 801 by the head 807. Therefore,
The amount of track deviation can be determined by checking the reproduction time difference between specific signals reproduced by the paired heads.

FIG. 9 is a diagram showing the relationship between the amount of track deviation and the reproduction time difference of a specific signal. If the horizontal axis represents the amount of track deviation and the vertical axis represents the playback time difference, the relationship between the two is expressed as 901.

Figures 8 and 9 show the state when the gaps of the magnetic heads constituting the pair head are accurately installed in the width direction of the recording track, but in reality, the gap between the magnetic heads constituting the pair head is set at f, 17 degrees. Due to variations, the positional relationship as shown in the figure may not be achieved.

FIG. 6 is a diagram showing the relative positional relationship between a recording track and a pair of heads in consideration of head mounting accuracy. In the same figure, A11. A21 is a recording track,
603 is a pair head composed of 604 and 605. The actual gaps between the magnetic heads constituting the pair of heads are not precisely aligned in the width direction of the recording track, as shown in FIG. When such a head reproduces a specific signal, even when the paired heads are on-track, the reproduction time difference between the specific signals reproduced from each head does not become zero. In the attached state shown in the figure, the time it takes for the head 604 to reproduce a specific signal is faster than the time it takes for the head 605 to reproduce it.

FIG. 7 is a diagram showing the relationship between the reproduction time difference and the amount of track deviation when a specific signal is reproduced with the head configured as shown in FIG. 6. In the figure, 901 shows the relationship between the playback time difference and track deviation when the gap position of the paired head is set accurately, and 701 shows the relationship between the two when the paired head shown in FIG. 6 is used. This is a diagram.

If control is performed so that the playback time difference becomes zero, the characteristic 701 will be stabilized at the position 702.

As a method for correcting such mounting errors of each head, there is a method proposed in Japanese Patent Application No. 77751/1983. This method involves scanning a head across a recording track, detecting the reproduction time difference of a specific signal at the time when the maximum value of the reproduction signal reproduced at this time is detected,
This method uses this time difference as the base p value for tracking control.

Problems to be Solved by the Invention However, in the conventional method described above, for example, the operation to correct the installation error of each head is performed immediately after pressing the play button, so when the number of paired heads increases, it is necessary to calibrate each head. The drawback was that it took too much time.

This kind of operation is particularly useful for business-use V
Not preferable in TR.

FIG. 5 shows an example of a head configuration used for each purpose. In the figure, 501 is a magnetic tape.

It is assumed that T1 to T4 are recording tracks recorded by a pair of heads, and each recording track has track curvature due to mechanical error. On such magnetic tape,
When editing is performed on a deck with other track curvatures, continuity of recording tracks cannot be obtained at the editing point.

In order to obtain continuity of the recording track at the editing point,
It is necessary to record information signals with the same track curvature as that recorded on the magnetic tape, and the head configuration shown in FIG. 5 is used to achieve this. In the same figure, 502 is a leading fixed head;
503 is a movable head for recording, 504 is a fixed head for monitoring, and each head is a pair head. Here, the fixed head is a head fixed on a rotating drum, and the movable head is a head fixed on an electromechanical transducer. The movable head is movable in the width direction of the recording track, that is, in the tracking direction. As for the operation during editing, if the preceding fixed head obtains information on the bending of the recording track that has already been recorded and supplies that bending information to the movable head 503, the movable head 503 can detect the bending of the track that has already been recorded. Recording tracks can be formed with the same curvature. Reference numeral 504 is a monitor head for checking recording, which checks whether an information signal is recorded or not, and also checks whether the tracking error signals reproduced from the fixing heads 502 and 504 are equal. You can also check whether the track is recorded with the same curvature as the recording track.

The head configuration shown in FIG. 5 requires three paired heads. In reality, in a deck configured to wrap tape 180 degrees on a rotating drum, each head and one
Three more heads are required 80 degrees apart, for a total of six paired heads. If the method of calculating the maximum value of the reproduced signal for each of these six pair heads and correcting the installation error of each head is performed, the time for correction will increase accordingly.
As already explained, commercial VTRs that emphasize scanning performance
That's not good.

In the present invention, during reproduction or during recording using the recording method explained in FIG. Installation of v! It is an object of the present invention to provide a tracking error signal generating device for correcting the mounting error of each pair of heads without performing a complicated operation of correcting the difference.

Means for Solving the Problem In order to achieve this object quickly, the tracking error signal generating device of the present invention provides
means for measuring the reproduction time difference of each specific signal reproduced from the magnetic head, and adjusting the error in the mounting position of the first and second magnetic heads in the rotational direction to the reproduction time difference reproduced by each pair of heads. Add a constant value to,
Alternatively, it has a configuration in which a precent value setting means for subtraction is provided.

Effect of the present invention With the above configuration, the value corresponding to the installation error of each magnetic head constituting the pair head can be set as the value of the preset value setting means at, for example, the manufacturing port 17 of the deck. The installation error of the magnetic head can be read and corrected to 1 m IL.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram of the entire reproducing circuit including the tracking error signal generating circuit according to the present invention. In the figure, At and A2 are magnetic heads, and the paired head is t.
It consists of one piece. B1. Similarly, each magnetic head of B2 forms a pair head of +7.7.

Each circuit from 201 to 204 is a head amplifier circuit, and amplifies the signal reproduced from each magnetic head. 20
5 and 206 are analog switches, which alternately select the signal F1 generated by the AI head (i is 1 or 2) and the Bi head by the head switching signal (H, SW double signal) supplied from the terminal 209. Each extracted signal is supplied to the reproduced signal processing circuit 207, demodulated into a normal video signal, and outputted to the video signal generator 208.The output signals of the analog switches 205 and 206 are processed by the specific signal separation circuit 210. , only the specific signals already explained are separated and extracted.

These signals are sent to the tracking error signal generation circuit 211.
is supplied to the terminal 21 by detecting the playback time difference of the specific signal.
2 as a tracking error signal.

FIG. 1 shows a block diagram of a tracking error signal generation circuit showing a first embodiment of the present invention. This circuit block is the tracking error signal generation circuit 21 shown in FIG.
FIG. 1 is a detailed block diagram of FIG. Further, FIG. 3 shows waveforms at various parts in FIG. 1, and the same symbols in both figures indicate the same signals. A first embodiment of the present invention will be described below with reference to both drawings.

In FIG. 1, from terminals 101 and 102, a specific signal (a) obtained from the specific signal separation circuit 210 in FIG.
and (b) are supplied and input to the gate circuit 103. The gate circuit 103 receives (e) or () from the input signal.
The signals in g) are created and output, and the method for creating these signals will be explained using FIG.

A specific signal (a) with a period T is a flip-flop circuit (
(not shown) to obtain the trust';''f(c).

Similarly, from the other 1.5 constant multiplier (b), use a flip-flop circuit to set the signal (d) to 1. Then, using a flip-flop circuit, Sent on the rising edge of signal (C), signal (d)
A signal (e) can be obtained that is reset at the falling edge of . The value of the difference between the high level period 302 and the low level period 303 of the signal (e) is the value of the difference between the signals (a) and (b).
It changes at a value twice the time difference 301 between the two. because,
The period between rising edges of signal (e) is always 2T, and the timing of falling edges is determined by the pulse position of signal (b), so signal (b) has only the value indicated by 301 with respect to signal (a). 3o2 when played late
The period of is longer than the period T by the time indicated by 301,
Conversely, the low level period 303 is shorter than the period T by the time indicated by 301. Therefore, the time difference between 302 and 303 changes by twice the playback time difference 301.

When signal (b) is in a position advanced relative to (a), signal (d) becomes signal (f), resulting in signal (e)
becomes as shown by signal (g). At this time, the high level period 305 is shorter than the low level period 306.

In addition, in order to maintain the polarity of signals (c) and (d), and (c) and (f) in a constant relationship as shown in the figure, the signal (C
It is sufficient to reset the signal (d) or (f) at a position after a certain time delay 304 from the falling edge of ). The signal (h) is a signal obtained by dividing the signal (C) in half, and has a period of 4T.

The output signal (e) or (g) of the gate circuit 103 shown in FIG. 1 is created by the method described above and input to the AND circuit 104. One input terminal of the AND circuit 104 has
Signal (h) is input. The output signal of the AND circuit 104 is input to an AND circuit 107 via an AND circuit 106 and an inversion circuit 105.

A clock signal of several tens of MHz is input from a terminal 108 to the other input terminals of the AND circuits 106 and 107.

The output signal of the AND circuit 108 is output as a clock signal only during the period 302 or 305 shown in FIG. 3, and is supplied to the amplifier input terminal of the up/down counter 109. Further, the output signal of the AND circuit 107 is output as a clock signal only during the period indicated by 303 or 306, and is supplied to the down terminal of the circuit 109. Taking signal (e) as an example, the clock is amplified and counted for a period of 302, and is down-counted for a period of 303.

Therefore, the output value 110 of the up/down counter 109 is a value corresponding to the reproduction time difference of the specific signal. A latch circuit 111 latches the value of the output signal 110 of the up/down counter at the falling edge of the signal (h). The latched value is converted into an analog signal by the D/A converter 112 and outputted to the terminal 212 as a tracking error signal.

The up/down counter 109 is loaded with a preset value at the rising edge of the signal (h).

The preset values are indicated by 116 and 117)
(++' The value set by the f setting means is selected by the switch circuit 115 which is switched according to the polarity of the H and SW multiplied signals supplied from the terminal 209, and is supplied to the up/down counter 109. Preset value setting Means 116
, 117 are non-volatile devices such as dip switches.

The preset value setting means 116 is for correcting the mounting error of the paired head (1) shown in FIG. This is to correct the installation error of the paired head.

When using multiple paired heads, use the conventional method described above for any one paired head, that is, scan the head across the recording track and identify the point at which the maximum value of the reproduced signal is detected. It is necessary to use a method in which the signal playback time difference is used as a value for subsequent tracking control.

This is because the recording position of the specific signal is 60 as shown in FIG.
1 and 602, the magnetization trajectories recorded by paired heads that are not aligned accurately in the width direction of the recording track and have installation errors will be difficult to record because the recording of a specific signal (, However, for other paired heads that scan the same recording track, it is only necessary to know the relative installation error for the paired head configured for the recording trunk. Become.

Therefore, if the paired heads AI and A2 shown in FIG. 2 perform the above-described calibration on the recording track, the precent value setting means 116 shown in FIG. 1 may have a fixed value. For example, if the up/down counter 109 is an 8-bit counter, the precent value of the preset value setting means 116 may be a value of 80 in hexadecimal. The preset value setting means 117 sets a value that takes into account the installation error between the pair of ALA2 heads, the 7D head, and the B1, B2 head pair, using a method described later. By providing such a preset value, a tracking error No. 43 is outputted to the terminal 212, taking into account the mounting error of each pair of heads.

A single point JI'J' (circuit block surrounded by 3A in Fig. 1 is an adjustment circuit added when adjusting a preset value. In the same figure, 119 is an inverting circuit, and 120 and 121 are latch circuits. The circuit 122 and 123 are display circuits that display the values of the latch circuit, and are composed of, for example, a 7-segment display circuit.The latch circuit 120 latches the input signal at the falling edge of the H, SW signal. 121 latches the input signal at the rising edge of the H65W signal.Therefore, the display circuit 1 outputs each tracking error signal obtained by reproducing the pair of heads A1 and A2 and the pair of B1 and B2 heads.
22 and 123, respectively. 124
is an envelope maximum value display circuit that displays the maximum value of the reproduced RF signal inputted from the terminal 125; for example, the amplitude of the reproduced RF signal may be observed with an oscilloscope.

In the above-mentioned envelope maximum value display circuit i1,7 configuration, the preset value is +11! Explain the steps to do this. First, the tracking volume is turned to adjust the level of the reproduction RF signal of the pair of heads Al and A2 to the maximum level, and the value of the display circuit 122 at this time is stored. And then,
B1. The tracking volume is adjusted so that the reproduced RF signal of the pair head B2 becomes maximum, and the value of the display circuit 123 at this time is stored. Then, the precent value setting means 11 calculates the value obtained by subtracting the values of the circle display circuits 122 and 123.
The value added to the preset value set in step 6 may be set as the value of the preset value setting means 117. By performing such adjustment, the installation error between the two paired heads can be adjusted.

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

FIG. 2 is a diagram showing a second embodiment of the present invention.

In the same figure, an output signal 110 of the down-down counter 109 shown in FIG. 1 is inputted from a terminal 401. tt
i, its, and 117 are the same as each circuit already explained in FIG. 1, 111 is a latch circuit, 118 is a circuit for adjusting a preset value, and 117 is a preset value setting means. 402 is a microcomputer, which includes a central processing unit 403, ROM 404, RAM 405,
It is composed of a D/A converter 406 and the like. Brise,.

The adjustment method of the output value setting means 117 is the same as the method already explained using FIG. Microcomputer 402
Now, the launch circuit 111 during scanning of each pair head
The output value of is stored in RAM.

Then, when outputting it as a tracking error signal, it is sufficient to add or subtract the value of the preset value setting means 117 read at an appropriate time and output it to the terminal 407 as a tracking error signal. Using the microcomputer 402 not only eliminates the need for the switch circuit 115 and the preset value setting means 116 shown in FIG. It has the advantage of being able to process.

In addition, in the first and second embodiments of the present invention, the case where the number of preset value setting means is one or two was explained, but when the number of pair heads increases, the number of preset value setting means is increased. It is clear that the mounting error of each pair of heads can be corrected using the same method (ρ).

Effects of the Invention As is clear from the above explanation, according to the present invention, by providing a precent value setting means for correcting the attachment error of each head constituting the throat to the pair, the The maximum value of the playback output is detected by crossing the recording track, and the specific value at that time 43
There is no need to perform 7M sloppy operations such as checking the reproduction time difference between the numbers, and the installation error can be easily known.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a tracking error signal generating device showing a first embodiment of the present invention, FIG. 2 is an overall block diagram of a regeneration circuit including the tracking error signal generating device according to the present invention, and FIG. 1 is a waveform diagram of each part, FIG. 4 is a block diagram showing a second embodiment according to the present invention, FIG. 5 is a diagram showing the relative positional relationship between a pair of heads used for various purposes and a recording track, FIG. 6 is a diagram showing the installation error of each magnetic head that makes up the paired head, and FIG. 7 is a diagram showing the relationship between the amount of track deviation and the reproduction time difference of the specific signal when a specific signal is reproduced by a pair of heads with installation errors. , FIG. 8 is a diagram showing the relative positional relationship between the paired head and the recording track, FIG. 9 is a diagram showing the relationship between the reproduction time difference of a specific signal reproduced by the paired head and the amount of track deviation, and FIG. 10 is a diagram showing the relationship between the pair head and the track deviation amount. FIG. 3 is a diagram showing an example of a recording format using the . 104, 106. 107...AND circuit, 105.
119--inverting circuit, 109--up/down counter, 111,120.121--launch circuit,
112.@D/A converter, 205.20Ef...analog switch, 403.Central processing unit,
T1. T2-Excellent recording track, 501... Magnetic tape, 502, 503. 504, 603... Pair head. Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures Figures H Rack Haha

Claims (1)

[Claims] In a magnetic recording/reproducing device having two or more pairs of paired heads each including a first and second magnetic head having different azimuth angles, each specific signal reproduced by the first and second magnetic heads of each paired head. means for measuring a reproduction time difference between the pair of heads, and adding or subtracting a certain value to the reproduction time difference reproduced by each pair of heads for adjusting an error in the mounting position of the first and second magnetic heads in the rotational direction. 1. A tracking error signal generating device, comprising a preset value setting means for setting a tracking error signal.