JPH02265009A - Tracking controller - Google Patents

Abstract

PURPOSE:To shorten the time for taking the tracking by setting correction data which is set, based on a difference between tracking error data and piezo- driving data to an arithmetic means so as to satisfy a prescribed condition. CONSTITUTION:Tracking error data inputted to an input terminal 101 is inputted to a data generating circuit 102, and to the data generating circuit 102, piezo- driving data 108 which passes through a delaying circuit 106 is also inputted. The data generating circuit 102 determines an arithmetic quantity for bringing an error being a difference of two data inputted by a head switch 104 and a counter 103 close to zero. The arithmetic quantity determined by the data generating circuit 102 is added to the delayed piezo-driving data by an adder 105, and the piezo-driving data brought to arithmetic processing passes through a delaying circuit 107 and sent to a driving circuit of an electro-mechanical converting element, and also, fed back to the data generating circuit 102 again. By executing successively and repeatedly this operation, a tracking control is executed.

Description

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

Conventional technology In a magnetic recording/reproducing device (hereinafter simply referred to as a VTR), when reproducing an information signal recorded on a recording track of a magnetic tape, a reproducing head on-tracks the recording track and performs reproduction scanning. 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 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, 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 configure a control system that can follow track bending.

A conventional tracking control device will be explained below.

FIG. 7 shows a block diagram for bringing the magnetic head on-track using an electro-mechanical conversion element.
The reproducing head 701 is mounted on a piezoelectric element 702 which is an electro-mechanical conversion element. 703 is a reproduction amplifier, and 704 is a reproduction signal processing circuit, which processes the signal reproduced by the reproduction head 701, converts it into the same form as the original signal, and outputs the signal from the terminal 705. Output. Furthermore, from the reproduced signal processing circuit 704,
A tracking error signal for tracking control included in the reproduction signal from the reproduction head 701 is output. The output tracking error signal is input to a tracking detection circuit 706, which processes the tracking error signal and outputs tracking error data corresponding to the amount of track deviation of the reproducing head.

The output tracking error data is input to the piezo drive data calculation circuit 707, and the piezo drive data calculation circuit 707 calculates data for driving the piezo piezoelectric element based on the input tracking error data.
A piezo drive signal is output to piezo drive circuit 708. The piezo drive circuit 708 applies a DC voltage to the piezoelectric element 702 according to the piezo drive signal.

FIG. 8 is a block diagram of the piezo drive data calculation circuit 707. In FIG. 8, 801 is a terminal for inputting tracking error data, and a comparison calculation circuit 802 compares the data input from the terminal 801 with the piezo drive data output from the delay circuit 804, and uses the result of the comparison. Based on this, a correction signal (+1 or -1) is created, added to the piezo drive data, slightly corrected, and replaced with piezo drive data 806. The modified piezo drive data is delayed by delay 0 circuit 805, sent to piezo drive circuit 708, and fed back to delay circuit 804. The conventional method is to repeat this operation as needed to perform tracking control.

Problems to be Solved by the Invention However, in the above method, as shown in the operation example in FIG.
03 is changed one step at a time centering on the on-track point as shown in the scanning trajectory 904 by the first calculation.
By repeating this calculation, the playback head will be able to on-track on the recording track as shown in the scanning trajectory 905, but since corrections are made at a fixed rate in response to changes in the pattern of the recording track, it will be difficult to follow the curve. This takes time, and if the playback head and recording track are misaligned by a large amount, a correction step equal to the misalignment is required;
The problem was that it took a long time to follow the track bend.

SUMMARY OF THE INVENTION In order to solve the above-mentioned conventional problems, it is an object of the present invention to provide a tracking control device that can bring a magnetic head onto a recording track in a short time.

Means for Solving the Problems To achieve this object, the present invention provides a magnetic head mounted on an electro-mechanical transducer and reproducing video signals recorded on a recording rack of a magnetic tape; Tracking error detection means for detecting track deviation of the magnetic head; calculation means for calculating data for driving the electro-mechanical conversion element based on the output of the tracking error detection means; and means for driving the electro-mechanical conversion element. and the calculation means is configured such that the piezo drive data in the (n-1)th scan after the track bending following operation of the magnetic head is started is P(n-1) and 1.
P by the value of tracking error in one scan
It is composed of arithmetic means for performing the arithmetic operation of (n-1)±K(n).

Further, the calculation means adjusts the value of m to the target value by changing the value of m such that the absolute value of the difference between the output of the dragging error detection means and the input of the driving means of the electro-mechanical conversion element becomes 2 m or less. It consists of arithmetic means for convergence.

Further, the calculation means is configured to change the amount of calculation by determining the integral value of the difference between the output of the tracking error detection means and the input of the drive means of the electro-mechanical conversion element.

Effects The present invention has the above-described configuration, and by changing the amount of calculation based on the input tracking error data, when the tracking error data becomes large, the calculation process is performed with a value of K (n) larger than ±1. The electro-mechanical transducer 2 magnetic head can be pulled into an on-track state in a short time.

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

In FIG. 1, 101 is an input terminal for the dragging error data obtained from the tracking error detection circuit;
02 is a data generation circuit, 103 is a counter, 104 is a head switch that outputs a head switch signal, 105 is an adder, 108. 107 is a delay circuit, and 109 is an output terminal connected to a drive circuit of the electro-mechanical conversion element.

The operation of the dragging control device of this embodiment configured as follows will be described below.

First, dragging error data input to the input terminal 101 is input to the data generation circuit 102, and piezo drive data 108 that has passed through the delay circuit 106 is further input to the data generation circuit 102. Data generation circuit 102
Now, the amount of calculation to bring the error, which is the difference between the two data inputted by the head switch 104 and the counter 103, close to zero is determined. The calculation amount determined by the data generation circuit 102 is added to the delayed piezo drive data by an adder 105. The processed piezo drive data is sent to the electro-mechanical conversion element drive circuit through the delay circuit 107 and fed back to the data generation circuit 102 again. Tracking control is performed by sequentially repeating this operation.

FIG. 2 shows a flowchart of a tracking control device showing a first embodiment of the present invention.

In FIG. 2, 201 is a setting unit for setting the initial value of piezo drive data for driving the electro-mechanical conversion element; 202
is an input section for inputting tracking error data, 203
is a comparison unit 204 that compares input tracking error data and piezo drive data delayed by one frame;
205 is a correction data initial value setting unit that sets correction data for n=1; 206 sets correction data when n≠1; A correction data setting section 207 is a comparison section that compares the set correction data and an error value, 208 is a comparison section 20
A correction data setting section 209 sets correction data based on the comparison result of 7, an addition section 209 adds piezo drive data and correction data, and a delay section 210 delays the piezo drive data by one frame.

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

First, if n is the number of times the playback head scans the recording track, the setting section 201 sets the initial value of the piezo drive data, and the input section 202 sets the tracking error data X (
n) is input. The input tracking error data X (n) is converted into piezo drive data P (n
-1).

If X (n) =P (n -1) then P(n-1)
The piezo drive data is sent to the delay circuit 210.

If X (n)≠P(n-1), the determining unit 204 is operated to determine whether n=1.

If n=1, the correction data initial value setting unit 205 sets
Based on the difference between (n) and P(n-1), the amount of calculation (hereinafter,
The initial value K(1) of the correction data) is IX(1)-
P(0) l /2 is set, and the adder 209 sets P(
n-1). If n≠1, the modified data generation unit 206 sets K (n) such that K(n-1)≧K(n)-11= by bit shifting. The comparison unit 207 compares the set K(n) with the error value obtained by the comparison unit 203, and if the error value becomes smaller due to K(n), the addition unit 209 adds it to P(n-1). be done. If the error value becomes large, the corrected data setting section 208 performs the operation K (n) = K (n-1) and sends it to the addition section 209. The data obtained by the addition section 209 is sent to the delay section 210 and delayed, and sent as piezo drive data to the drive circuit of the electro-mechanical conversion element and fed back to the comparison section 203. Tracking control can be performed by sequentially repeating this operation.

As described above, according to this embodiment, by setting the correction data K(n) and setting it so that K(n-1)≧K(n) is satisfied, the piezo drive data is adjusted to the target value. It is possible to approach the object rapidly, which speeds up the tracking time.

FIG. 3 shows a block diagram of a tracking control device showing a second embodiment of the present invention.

In FIG. 3, 301 is tracking error data 1
Comparison circuit 302 for comparing 01 and piezo drive data
is a data generation circuit and 21 (m: a positive integer greater than or equal to 0)
to occur. 303 is a reset circuit that resets each operation, 304 is a discrimination circuit that compares the result of the comparison circuit 301 with the data generated by the data generation circuit 302, and determines whether the result is large or small; 305 is an adder; Based on the result of the presence determination circuit 304, 2m is added to P(n-1). 306 and 307 are delay circuits.

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

First, the tracking error data 101 is transmitted to the comparison circuit 30.
1 and compared with the piezo drive data. At the same time, the reset circuit 303 initializes the data generation circuit 302 (m=o) and calculates 2m. Comparison circuit 30
The comparison result of 1 (absolute value α(n) of the difference) and the data 21 generated by the data generation circuit 302 are sent to the discrimination circuit 304, where they are compared in magnitude and held m until the condition α(n)≦21 is satisfied.
change. If the conditions are met, the adder 305 adds P(
n-1) Above 2- (determined by the comparison circuit) is performed, and is fed back to the comparison circuit 301 together with the drive circuit of the electro-mechanical conversion element via delay circuits 306 and 307.

Tracking control can be performed by repeatedly performing this scanning.

FIG. 4 shows a flowchart of a tracking control device showing a second embodiment of the present invention.

In the figure, 201 is a setting unit for setting the initial value of piezo drive data for driving the electro-mechanical conversion element, 202 is an input unit for inputting tracking error data, and 203 is a unit that is delayed by one frame from the input tracking error data. A comparison section 210 for comparing the calculated piezo drive data with the calculated piezo drive data is a delay section that delays the calculated piezo drive data by one frame, and the above is the same as that shown in FIG. What is different from FIG. 2 is a correction data setting section 4 that sets correction data 21.
01, a comparison section 402 that compares the absolute value of the difference between the tracking error data and the piezo drive data delayed by one frame with the corrected data 2t, and change the value of m based on the comparison result of the comparison section 402. The difference is that a changing section 403 is provided, and an adding section 404 corrects the piezo drive data.

The operation will be explained below.

First, the setting section 201 sets the initial value of the piezo drive data, and the input section 202 sets the tracking error data X (n
) is input. The input tracking error data X (n) is compared with the piezo drive data P (n-1) delayed by one frame in the comparator 203, and X (n) =
If P (n −1), it is sent to the delay unit 210 and
If (n)≠P(n-1), the correction data setting unit 401
sent to. The setting unit 401 sets correction data 21 (m: a positive integer greater than or equal to 0) according to the value of In. The set correction data is sent to the comparison unit 402. Comparison section 40
In step 2, the absolute value α of the difference between X(n) and P(n-1) is determined based on the subtraction force a calculation information obtained from the head switch 104 and the counter 103, and the result and the correction data setting section 401 A comparison is made with the obtained corrected data. If the condition is satisfied by the result of the comparison unit 402 (α<2
In m), piezo drive data and correction data are added in addition section 404 and sent to delay section 210 . If the condition is not satisfied (α≧21+), the change part is 403 and m=
The operation m+1 is performed and fed back to the modified data setting section 401. The adder 404 adds 2m to the piezo drive data delayed by one frame. The piezo drive data subjected to the arithmetic processing is delayed by one frame by the delay unit 210, and is sent to the drive circuit of the electro-mechanical conversion element and fed back to the comparison circuit 203. Tracking control can be performed by sequentially repeating this operation.

As described above, according to this embodiment, the calculation step is changed according to the error value, and the change is performed at 2fi, thereby making it possible to speed up the tracking time.

FIG. 5 shows a block diagram of a tracking control device showing a third embodiment of the present invention.

In FIG. 5, 501 and 503 are comparison circuits, 502 is an integration circuit, 504 is a data generation circuit, 505 and 506 are delay circuits, 507 is an adder, and 508 is a data input terminal from ROM data.

The operation of the tracking control device configured as described in section 1 will be described below.

First, the absolute value α(n) of the difference between the tracking error data and the piezo drive data obtained by the comparator circuit 501 is sent to the integrating circuit 502 and integrated within the 11-rack period. The obtained integral value is sent to the comparator 503 and input terminal 50
8 is compared with a preset value β. The obtained result is sent to the data generation circuit 504, and the amount of calculation is changed based on the result. The obtained calculation amount is added to the piezo drive data by the adder 507, and the delay circuit 505.
The signal sent to the drive circuit of the electro-mechanical conversion element via 506 is also fed back to the comparison circuit 501 .

Tracking control can be performed by repeating this operation.

FIG. 6 shows a flowchart of an l-racking control system illustrating a third embodiment of the present invention.

In the figure, 201 is an initial value setting unit for piezo drive data for driving an electro-mechanical conversion element, 202 is an input unit for inputting racking error data, and 203 is an input unit for inputting racking error data.
210 is a comparison unit that compares input tracking error data and piezo drive data delayed by one frame;
2 is a delay section that delays the calculated piezo drive data by one frame, and the other components are similar to those shown in FIGS. 2 and 3.

What is different from FIGS. 2 and 4 is that an integrator 601 is provided to integrate the absolute value of the difference between tracking error data X (n) and piezo drive data P (n-1), and The difference is that the magnitude of the obtained integral value is determined and the amount of calculation is changed to perform dragging control. The operation will be explained below.

Tracking error data X obtained by comparison section 203
Absolute value α of the difference between (n) and piezo drive data P(n-1)
(n) is integrated for each frame by an integrator 60J, and the result of the integration is compared with the value β by a comparator 602. As a result, if Σα(n)>β, the correction data setting section b60
4, set the data that can be roughly corrected, and adder 6.
05, it is added to the piezo drive data. If Σα(n)≦β, the correction data setting unit a603 sets data that allows fine correction, and the adder 605 adds it to the piezo drive data. As rough correction data, set the correction data by setting any bit in the 8-bit correction data to 1 and shifting it to the right one bit at a time, and as detailed correction data, set the correction data set above. Corrected data is set by calculating ±1 based on the data.

The piezo drive data obtained from the adder 605 is delayed by one frame by the delay circuit 210 and sent to the drive circuit of the electro-mechanical conversion element, and is also fed back to the comparator 203. Tracking control can be performed by repeatedly performing this operation.

As described above, according to this embodiment, the magnitude of the integral value Σα(n) obtained by integrating the absolute value of the difference between the tracking error data and the piezo drive data is determined by the value β. By understanding the value, it is possible to quickly follow changes in track bending, and the time for tracking can be shortened.

Effects of the Invention As described above, the present invention sets the correction data K(n) set based on the difference between the tracking error data and the piezo drive data to the calculation means under the condition that K(n-1)≧K(n). By setting satisfactorily, the piezo drive data can be quickly changed to the target value, and the time for tracking can be shortened.

Further, by changing the correction data setting in the arithmetic means by 21+, the correction data can be set by bit shifting, so that the time required for tracking can be shortened.

Furthermore, by integrating the absolute value of the difference between the tracking error data and the piezo drive data in the calculation means and determining the magnitude of the integrated value, correction is made in large steps when the error is large, and in small steps when the error is small. Since the data can be set, the time required for tracking can be shortened, and changes in track curvature can be quickly followed.

[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 flowchart of the same embodiment, and FIG.
The figure is a block diagram of a tracking control device according to a second embodiment of the present invention, FIG. 4 is a flowchart of the same embodiment, FIG. 5 is a block diagram of a tracking control device according to a third embodiment of the present invention, and FIG. The figure is a flowchart of the same embodiment, FIG. 7 is a block diagram of a tracking control system including a conventional tracking control device, FIG. 8 is a block diagram of a conventional tracking control device, and FIG. 9 is an operation of a conventional tracking control device. It is a diagram. 102.302,504...Data generation circuit, 103
...Counter, 104...Head switch, 3
03... Reset circuit, 304... Discrimination circuit,
502... Integrating circuit, 503... Comparing circuit, 2
05.206...Computation amount K (n) setting section, 401.
402, 403... Correction data setting section. Name of agent: Patent attorney Shigetaka Awano Funeral map for one person: 3rd ward 3θ Otsu 7, + Figure f? 0M take diagram / 9θ2

Claims (3)

[Claims] (1) A magnetic head mounted on an electro-mechanical transducer and reproducing a video signal recorded on a recording track of a magnetic tape, a tracking error detection means for detecting a track deviation of the magnetic head, and this tracking error detection It has a calculation means for calculating data for driving the electro-mechanical conversion element based on the output of the means, and a driving means for driving the electro-mechanical conversion element, and the calculation means calculates n by the number of times the recording track is scanned. Then, the number of scans (n-
1) The piezo drive data in the second scan is P(n-1
), the amount of calculation K(n) is set according to the value of the tracking error which is the output of the tracking error detection means in the n-th scan, and the calculation of P(n-1)±K(n) is performed, and the amount of calculation is A tracking control device characterized in that K(n) is changed depending on the number of scans n. (2) The calculation means calculates the value of m (m:
2. The tracking control device according to claim 1, wherein the tracking control device changes a positive integer of 0 or more. (3) The calculation means calculates that the integral value Σα(n) within one track period of the difference α(n) between the output of the tracking error detection means and the input of the drive means of the electro-mechanical conversion element is a set value β. 2. The tracking control device according to claim 1, wherein the amount of calculation is changed by setting K(n)=1 when it is smaller than .