JPH0380414A - Tracking controller - Google Patents

Abstract

PURPOSE:To provide the tracking controller which can shorten the time for computation by comparing the tracking error data to be inputted with a tracking reference value which is the tracking error data at the time of on-tracking. CONSTITUTION:A tracking error detecting means 106 detects the off-tracking of a magnetic head 101 mounted on a piezoelectric element 102 with respect to the recording tracks on a tape. The detected tracking error data is inputted together with the reference value of the tracking from a terminal 110 to a comparing arithmetic circuit 111. The tracking reference value inputted from the terminal 110 is the tracking error data at the time of the on-tracking. The comparing arithmetic circuit 111 computes the difference between the tracking error data and the tracking reference value and inputs the result of the computation processing thereof to a function generating circuit 112. The processing time is shortened by as much as the processing to change the reference value of the comparing arithmetic circuit 111 is not executed. The scanning position of a playback head is thus retracted to the on-track position.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a tracking control device in a magnetic recording/reproducing device.

Conventional technology In a magnetic recording and reproducing apparatus (hereinafter simply referred to as a VTR), when reproducing information signals recorded on a recording track, a reproducing head is scanned so as to be on-track on the recording track. Tracking control is required.

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 by superimposing it on the video signal on the recording track, and during playback, each pilot signal is read from both adjacent tracks of the main track that the head is scanning for playback. There is a method of obtaining a tracking error signal by comparing the reproduction levels of the signals. In this method, a tracking error signal can be obtained over the entire recording track, so the reproducing head is mounted on an electro-mechanical transducer made of a piezoelectric element, etc., and the mechanical position of the head is changed using the tracking error signal. By doing so, it is possible to construct a control system that can follow just like a truck.

A conventional tracking control device using the above pilot signal will be explained below.

FIG. 8 shows a recording pattern on a magnetic tape.

A magnetic tape 803 is transferred in the direction of an arrow 802, and a recording track 801 is formed on the magnetic tape. Pilot signals f1 to f4 are recorded on the recording track 801 while being superimposed on the video signal. For example, the frequency of fl-f4 is set to the following value, fl=6. 5f) I f2= 7.5fH f3"10.5fn f4= 9.5fh Here, fl4 is the frequency of the horizontal synchronization signal (15,75K
H2).

FIG. 9 shows a block diagram of the tracking error detection circuit. As shown in FIG. 8, the operation of the tracking error detection circuit will be described by taking as an example the case where the reproducing head 804 is scanning the recording track B1. A reproduction signal output from the reproduction head 804 and amplified by an amplifier is inputted from the terminal 901. The high frequency band of the reproduced signal includes a reproduced video signal, and the low frequency band includes a reproduced pilot signal, and the reproduced pilot signal that has passed through the low-pass filter 902 is inputted to the balanced modulation circuit 903. To the balanced modulation circuit 903, f2 is input as a reference pilot signal from a terminal 910, and from the balanced modulation circuit 903, I
Signals with frequencies of f1-f2+ and 1 f3-f21 are output. Tuned amplifier 904 and detection rectifier circuit 9
06, a DC voltage proportional to the peak value of the signal component of Iff-f2+ (that is, fH) is obtained, and similarly, the tuning circuit 905 and the detection rectifier circuit 907 obtain If3-f2.
1 (that is, 3f1.l), a DC voltage proportional to the peak value of the signal component is obtained. A comparison circuit 90 compares these voltages.
8, the difference between these voltages is output from the terminal 909. That is, the track deviation of the reproducing head can be detected by the voltage output to the terminal 909. Furthermore, in practice, since track bending follow-up control is performed digitally, the voltage for detecting track deviation is generally converted into digital data by an A/D converter.

FIG. 7 shows a block diagram of a tracking control system for causing a magnetic head to perform on-track scanning using an electro-mechanical conversion element.

In FIG. 7, the reproducing head '1o1 is mounted on a piezoelectric element 102 which is an electro-mechanical conversion element.

103 is a regenerative amplifier. The high frequency component of the output signal of the regenerative amplifier 103 includes a reproduced video signal, and the reproduced signal processing circuit 104 passes the video signal, which is the high frequency component of the output signal of the regenerative amplifier 103, through a high-pass filter and outputs the reproduced video signal to the terminal 105. Output from.

On the other hand, the reproduced pilot signal is input to the tracking error detection circuit 10B.
6, as explained using FIG. 9, the reproduction pilot signal is processed and tracking error data corresponding to the amount of track deviation of the reproduction head is output. The piezo drive data calculation circuit 707 calculates data for driving the piezoelectric element 102 based on the tracking error data, and outputs a piezo drive signal to the piezo drive circuit 108. The piezo drive circuit 108 applies a DC voltage to the piezoelectric element 102 according to the piezo drive signal.

FIG. 10 is a detailed block diagram of the piezo drive data calculation circuit 707.

In FIG. 10, tracking error data is input from a terminal 1001. Comparison calculation circuit 1002 calculates the difference between tracking error data and piezo drive data 1006, and inputs the calculation result to function generation circuit 1003. The function generation circuit 1003 generates data (+1, O or -l) for slightly correcting the position of the electro-mechanical conversion element according to the output value of the comparison calculation circuit 1002, and the addition circuit 1004 generates data (+1, O or -l) for making a small correction in the position of the electro-mechanical conversion element. This corrected data is added to create new piezo drive data. The newly created piezo drive data is sent to the delay circuit 10.
It is delayed by one frame at 05, and the electricity is output through terminal 1007.
It is output to the drive circuit IO8 of the mechanical transducer element, and is also fed back to the addition circuit 1004 and comparison operation circuit 1002.

FIG. 11 shows how track bending is followed when track bending control is performed by a tracking control device including the conventional piezo drive data calculation circuit 707 shown in FIG. If there is a bend in the recording track as shown in the figure, and the playback head scans the track as shown in the scanning trajectory In the case of the figure, it becomes larger (or smaller) than the initial value), so the piezo drive data at point D1 is subjected to the calculation result E and converted to point D2, and the playback head moves as shown in the scanning trajectory ■. Scan to.

Tracking error data is obtained again from the playback head that scanned the scanning trajectory ■, and compared with the previous data (tracking error data obtained from the scanning trajectory ■), and based on the comparison result, the calculation processing result E is again calculated. By repeating this scanning, the reproducing head is brought on-track. This operation is repeated sequentially to perform tracking control (this is the conventional method).

Problems to be Solved by the Invention However, in the above conventional method, (1) the piezo drive data of one frame before is fed into the a comparison calculation circuit 1002; the reference value of the comparison calculation circuit 1002 changes due to the The tracking pull-in position of the playback head deviates slightly from the on-track position.

(2) Furthermore, it is necessary to calculate the difference between the tracking error data and the piezo drive data one frame before each time, which increases the number of calculations and takes a long calculation time.

(3) Furthermore, since the number of tracking reference values C increases in proportion to the number of samplings during one track scan of the playback head ζ, when the number of samplings is increased for the purpose of improving the accuracy of track bending tracking, A large amount of memory is required to store the reference values. There was a problem.

In order to solve the above conventional problems, the present invention reduces the number of calculations by calculating the difference between the tracking error data that is the output of the tracking error detection circuit and a fixed tracking reference value. It is an object of the present invention to provide a tracking control device that can reduce calculation time.

Means for Solving the Problems In order to achieve this object, the tracking control device of the present invention is provided in 11. tracking error detection means for detecting track deviation of a magnetic head mounted on the electro-mechanical conversion element; and tracking error data output from the tracking error detection means for driving the electro-mechanical conversion element. It has a drive data calculation means for calculating data, and an electro-mechanical conversion element driving means for driving the electro-mechanical conversion element according to the output of the drive data calculation means, and the drive data calculation means is configured to control the tracking A comparison calculation means for calculating the difference between the error data and the tracking reference value, a function generation means for outputting a set value according to the output value of the comparison calculation means, and the drive data calculation means for outputting the output data of the function generation means. It has an adding means for adding to the output of.

According to the above-described structure, the present invention can bring the scanning position of the reproducing head to the on-track position by comparing the input tracking error data with the tracking reference value which is the tracking error data at the time of on-track. Since the process of changing the reference value of the comparison calculation means is not performed, the processing time can be shortened.

Embodiment FIG. 1 shows a block diagram of a tracking control device in a first embodiment of the present invention.

In FIG. 1, a reproducing head 101 is mounted on a piezoelectric element 102, which is an electro-mechanical transducer. 1
03 is a regenerative amplifier. The high-frequency component of the output signal of the regenerative amplifier 103 includes a reproduced video signal, and the reproduced signal processing circuit 104 passes the video signal, which is the high-frequency component of the output signal of the regenerative amplifier 103, through a high-pass filter and outputs the reproduced video signal to a terminal. ) Output from 05. On the other hand, the reproduced pilot signal is transmitted to the tracking error detection circuit 10.
The tracking error detection circuit 106 processes the reproduction pilot signal and outputs tracking error data corresponding to the amount of track deviation of the reproduction head.

The piezo drive data calculation circuit 107 calculates data for driving the piezoelectric element 102 based on the tracking error data, and outputs the piezo drive signal to the piezo drive circuit 1.
Output on 08. The piezo drive circuit 108 applies a DC voltage to the piezoelectric element 102 according to the piezo drive signal.

In the piezo drive data calculation circuit 107, the terminal 109
Tracking error data obtained from the tracking error detection circuit is inputted from the terminal 110, and the tracking M#i value is inputted to the terminal 110. Comparison calculation circuit 11
1 calculates the difference between the tracking error data and the tracking reference value, and inputs the calculation result to the function generating circuit 112.

The function generation circuit 112 generates a data (+1, O or -1) for slightly modifying the piezoelectric element 0, according to the output value of the comparison calculation circuit 111, and the addition circuit 113
This correction data is added to the piezo drive data 115 to create new piezo drive data. The newly created piezo drive data is delayed by one frame in the delay circuit 114, outputted to the drive circuit of the electro-mechanical conversion element via the terminal 116, and fed back to the addition circuit 113.

The tracking operation of the tracking control device of this embodiment configured as described above will be explained.

First, the tracking error data inputted to the terminal 109 is inputted to the comparison calculation circuit 111 together with the tracking reference value A of the terminal 110. Here, the tracking reference value A input from the terminal 110 is tracking error data at the time of on-track. Comparison calculation circuit 111
Then, the tracking error data is subtracted from the tracking reference value A, and the arithmetic processing result E is output.

The arithmetic processing result E is input to the function generating circuit 112, and the function generating circuit 112 outputs +1 data if the arithmetic processing result E is E > O, and outputs -1 data if E > 0. If E = O, output the data of O,
It is input to the addition circuit 113. The adding circuit 113 adds the data obtained by the function generating circuit 112 and the piezo drive data 115 of one frame before. The result of the addition circuit 113 is delayed by a delay circuit 114, and the delayed piezo drive data is input to the electro-mechanical conversion element drive circuit 108 via the terminal 116, and the piezo drive data 115 delayed by one frame is added. It is fed back to circuit 113.

FIG. 2 is a diagram showing the reproducing head 202 scanning over the recording track 201. As shown in FIG. Piezo drive data is +
It is assumed that when the piezo drive data is changed to -l, the head shifts to the right in the drawing, and when the piezo drive data is changed to -l, the head shifts to the left in the drawing. In the figure, the number of samples is 4 (pieces/track), the tracking reference value is the tracking error value when on-track, and the tracking error data when the maximum envelope value is obtained is used as the tracking reference value. When the reference value of is set to X'7D' and the piezo drive data is set as shown in Fig. 3(a),
The scanning locus of the reproducing head 202 becomes as shown by the solid line (■) in FIG. 2, and the tracking error data at that time becomes as shown in FIG. 3(a). Here, new piezo drive data (FIG. 3(b)) is obtained from the output of the comparison calculation circuit 111 and the output of the function generation circuit 112, and the scanning locus of the reproducing head 202 becomes as shown by the solid line (■) in FIG. The tracking error data at this time is as shown in FIG. 3(b). moreover,
The tracking error data is compared with a tracking reference value, the piezo drive data is corrected, and the scanning locus (2) shown in FIG. 2 is scanned to obtain the image shown in FIG. 3(c). By sequentially repeating this operation, the playback head can control the on-track position and achieve tracking control that follows track bending.

As described above, according to this embodiment, by providing the tracking reference value A, there is no need to rewrite the comparison data, so that the processing time can be shortened.

Furthermore, when the number of samplings is four, only one memory is required instead of the conventional four, so the memory can be reduced. Furthermore, since there is no change in the tracking reference value, the on-track position of the playback head can be kept constant (the pull-in point is at the on-track position).

FIG. 4 is a detailed block diagram of a piezo drive data calculation circuit showing a second embodiment of the present invention.

In FIG. 4, tracking error data obtained from the tracking error detection circuit 106 is manually inputted from a terminal 109, and a tracking reference value is inputted to a terminal 110. The comparison calculation circuit 111 calculates the difference between the tracking error data and the tracking reference value, and inputs the calculation result to the function generation circuit 401. The function generation circuit 401 generates data (
+1, O, or -l), and the addition circuit 113 adds this correction data to the piezo drive data 115 to create new piezo drive data. The newly created piezo drive data is delayed by one frame in the delay circuit 114, outputted to the drive circuit of the electro-mechanical conversion element via the terminal 116, and fed back to the addition circuit 113. The above structure is the same as that of the first embodiment of the present invention.

The function generation circuit 40 is different from the first embodiment of the present invention.
1 is provided with a range (hereinafter simply referred to as a dead zone) in which 0 is output for the output E of the comparison arithmetic circuit tti.

The operation of the tracking control device of this embodiment configured as described above will be described below.

The function generation circuit 401 outputs +1 data if the comparison result E of the - comparison calculation circuit 111 is E>β, and E<-
If β, output data of -1, and E≦β and E≧−β
If so, output the data of 0 and send it to the adder circuit 113 as it is.
is input.

FIG. 5 is a diagram showing the characteristics of a function generating circuit of a tracking control device showing a second embodiment of the present invention.

In FIG. 5, the characteristics of the function generation circuit 401 are such that when the output data E of the comparison calculation circuit 111 is -β≦E≦β, a range is provided in which O is output. can be provided.

As described above, according to this embodiment, when the reproducing head is almost at the on-track position, the processing time can be shortened by the amount of time during which arithmetic processing for minutely modifying the piezo drive data is not performed.

FIG. 6 is a diagram specifically showing the relationship between track pitch, on-track position, and the above β.

In FIG. 6, 601 indicates a recording track, 602 indicates a dead zone portion, and 603 indicates an on-track position.

If the width of the recording track is Tp, then even if the scanning position of the reproducing head deviates from the on-track position by about Tp/10, the decrease in the envelope output is small. Therefore, let β be the amount of tracking error data corresponding to a track deviation of Tp/lo. By setting , the number of calculations can be reduced and the calculation time can be shortened.

As described above, according to this embodiment, if the deviation from the on-track position of the head scan is within about 1/10 rack, the processing time can be shortened by the time when no calculation processing is performed to minutely modify the piezo drive data. . This is particularly effective when using a wide playback head.

Effects of the Invention As described above, the present invention corrects the reviezo drive data by comparing the tracking reference value A with the tracking error data, thereby keeping the on-track position of the playback head constant (when the pull-in point is on-track). position), and by providing a dead zone, the number of calculations and calculation time can be shortened.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a tracking control device according to a first embodiment of the present invention, Fig. 2 is a pattern diagram explaining the tracking principle of the same embodiment, and Fig. 3 shows the tracking principle of the same embodiment due to tracking error. A data flow diagram explained using data and piezo drive data, FIG. 4 is the second embodiment of the present invention.
FIG. 5 is a characteristic diagram showing the input/output relationship of the function generating circuit of the embodiment, FIG. 6 is a recording track diagram for explaining the embodiment, and FIG. The figure is a block diagram of a conventional tracking control device, and FIG. 8 is a recording track diagram for explaining the conventional example.
FIG. 9 is a block diagram of a conventional tracking error detection circuit, FIG. 10 is a block diagram of a conventional piezo drive data calculation circuit, and FIG. 11 is a pattern diagram showing the following principle of tracking control. +01... Playback head, 102... Piezo piezoelectric element, Summer 06... Tracking error detection circuit, 107.
...Piezo drive data calculation circuit, 108...Piezo drive circuit, 111...Comparison calculation circuit, 112...Function generation circuit, 113...Addition circuit, 114...Delay circuit. Figure Figure ◇ I True data +f 10f -f ←f Correction data +f + 1 --------111111--1 Figure 11

Claims (3)

[Claims] (1) Tracking error detection means for detecting track deviation of a magnetic head mounted on an electro-mechanical transducer with respect to a recording track on a tape, and tracking error data that is the output of the tracking error detection means. a drive data calculation means for calculating data for driving the electro-mechanical conversion element; and a drive means for driving the electro-mechanical conversion element according to an output of the drive data calculation means, the drive data The calculation means includes a comparison calculation means for calculating the difference between the tracking error data and the tracking reference value, a function generation means for outputting a set value according to an output value of the comparison calculation means, and output data of the function generation means. and a delay means for delaying the piezo drive data obtained from the addition means, and the tracking reference value is a tracking error value at the time of on-track. Features tracking control device. (2) The function generation means outputs E from the comparison calculation means.
2. The tracking control device according to claim 1, wherein the tracking control device outputs zero when there is a relationship of β≧E≧−β with respect to the set value β. (3) The tracking control device according to claim 2, wherein the value of β is set to approximately 1/10 of the track pitch Tp.