JP2600006B2 - Magnetic recording / reproducing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a reproducing method for a high-density magnetic recording / reproducing apparatus.

[Prior Art] As a conventional magnetic recording / reproducing apparatus, for example,
Japanese Unexamined Patent Publication No. -50967 is known and is described as follows.

FIG. 8 is a diagram showing a magnetic head mounted state, and FIG. 9 is a block diagram showing a conventional magnetic recording / reproducing apparatus. 8th
As shown in the figure, a magnetic head 1 is mounted on a movable element 2 such as a piezoelectric element.
As shown in FIG. 9, in a reproducing apparatus in which the magnetic head 1 can be moved in the direction of the arrow in FIG. 8 by inputting a signal such as electricity to the movable element 2, , A signal generator 12 that can generate a step-like signal, and a detector 8
And an AD converter 18 for converting a signal from the generator 12 into a digital amount, a memory 9 capable of storing the output thereof, a computing unit 10 for performing a predetermined operation on the memory content, and a DA for converting the operation result into an analog amount. And a converter 11. Reference numeral 15 denotes a sampling signal generator, 14 denotes an amplifier, and 13 denotes reproduction mode switching means for operating switches SW1 and SW2.

When reproduction is started, first, the reproduction mode switching means 13 operates, whereby the switches SW1 and SW2 operate as shown by the broken lines. As shown in FIG. 10, a signal of several steps (three steps in this example) is generated from the step signal generator 12 in field units and applied to the movable element 2. Since the movable element 2 moves the head 1 in the track width direction according to the applied voltage, the head 1 scans the track 5 at a position such as a, b, and c in FIG. (While the head 1 scans the track 5 once (about 17 ms), the applied voltage is not changed.) At this time, the reproduction output from the head 1 is
As shown in FIG. 12, characteristic waveforms 16, 17, and 19 corresponding to the position of the head 1 are shown. At this time, the step signal voltage and the output waveforms 16, 17, and 19 are stored in the memory 9 at a predetermined sampling cycle, and the switches SW1 and SW2 are turned off (see b in FIG. 10).

Now, by associating the applied voltage from the step signal generator 12 with the corresponding head outputs 16, 17, and 19, the bending amount of the track 5 can be obtained by the calculator 10 as shown in FIG. 13, for example. it can. FIG. 13 shows a position where the maximum output of the reproduction outputs 16, 17, and 19 from the head 1 is set as an optimum track position, and a waveform 20 connecting each point smoothly is calculated.
It is generated at 10 and seeks track bending. In order to increase the accuracy with which the head traces the track with respect to the amount of track bending, the head must be used as a playback output
If you know the maximum playback voltage Vd to output,
The track shift amount may be calculated from the difference between the voltage value (set voltage value) V｀d and the maximum value during reproduction, and the difference may be eliminated. It is also assumed that the maximum value Vmax has been obtained as a signal during reproduction. In this case, if | V _d −V _max | ≦ ε (where ε is a small value), it is considered that the head almost traces the track.

The track bending amount thus obtained is stored in the memory 9 again.
To memorize. From point b in FIG. 10, switches SW1 and SW2 are set to O
FF, and the voltage to correct the amount of bending of track 5 is a DA converter
The voltage is applied to the movable element 2 every time the head 1 scans via 11.

Thereby, the best tracking can be performed without always vibrating the head 1.

When the running mode of the tape changes, a step signal is generated only at the moment of the change (sections c and d in FIG. 10), and a new correction signal is generated in the same procedure as above.

In the case of a VTR, the time required for one scan of the head is about 17 ms. Therefore, even if the scan is performed about 10 times, the step signal generation period is about 170 ms, which is not a problematic length for an image.

In the above, the track bend amount is learned only during the step signal generation period. As another example, the head output obtained by correcting the track bend during the beginning of the memory voltage application periods b to c in FIG. Compare the voltage with the design voltage value Vd,
It is checked whether the track bending correction voltage is sufficient, and if it is insufficient, the step bending voltage may be superimposed on the track bending correction voltage, and the track bending amount may be calculated again to improve the correction accuracy.

[Problems to be Solved by the Invention] The conventional magnetic recording / reproducing method is as described above. Even if the magnetic tape is recorded by the same magnetic recording device, the expansion and contraction of the magnetic tape and the change in the tension of the reproducing device are performed. For example, there is a temporal change in the track bend due to, for example, the track bend.
Therefore, it is necessary to cope with this change with time.

However, in the conventional method, as described in Japanese Patent Publication No. 1-50967, image quality is deteriorated for a certain period immediately after the start of signal reading, that is, during a period in which a step signal is generated. It is necessary to provide a step signal generation period during reproduction in order to follow a change over time in track bending, and the image quality is degraded each time.

Further, for example, in the case of a general home magnetic recording / reproducing device, etc., the magnetic tape to be reproduced is recorded by various magnetic recording devices, and since there is a difference in recording level between each device, the set voltage value Vd is There is a problem in that it cannot be uniquely determined, and the accuracy of track bending correction cannot be improved by comparison with a fixed value Vd. Furthermore, as a conventional method, JP-A-57-64325 is known.
It is also shown in the official gazette. However, in this method, the video head is moved to a normal tracking position by monitoring whether or not the size of the reproduced video signal has decreased in the same track. In this method, a time lag occurs between the monitored time and the time for actually moving the head based on the monitored time. For this reason, there is a possibility that the image quality may be deteriorated during the reproduction, and there is a problem that a high-quality reproduced image cannot be obtained.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to prevent a change in track bending over time without deteriorating image quality during reproduction and even for magnetic tapes having different recording levels. It is an object of the present invention to provide a magnetic recording / reproducing method which can obtain a good reproduced image.

[Means for Solving the Problems] In a magnetic recording / reproducing method according to the present invention, a magnetic head is mounted on a movable element, and an input signal such as electricity is externally applied to the movable element so that the magnetic head is mounted on a magnetic tape. In the method for performing magnetic recording / reproducing using a magnetic recording / reproducing apparatus which moves and tracks a track written on a movable element, a predetermined first pattern signal is applied to a movable element so that a locus of the magnetic head becomes a first pattern. And a step of changing a track pitch for a track different from the track that output the first pattern signal while keeping the first pattern as it is.
Move the magnetic head in the track width direction within a range of 1/3 or less, read the reproduction signal at that time, detect the position of the magnetic head where the reproduction signal is maximum within the movement range, and move the magnetic head to that position. Necessary to move the, the step of inputting a second pattern signal to the movable element, and leave the second pattern as it is, for a track different from the track that output the first and second pattern signals Move the magnetic head in the track width direction within a range of 1/3 or less of the track pitch, and read the reproduced signal at that time,
Detecting the position of the magnetic head at which the reproduction signal is maximum in the moving range, and inputting a third pattern signal necessary for moving the magnetic head to the position to the movable element. It is.

[Action]

According to the above method, the magnetic head is moved within a predetermined range in the track width or the magnetic tape width direction, and the position of the magnetic head at which the reproduction signal is maximized within the moving range is detected, and a pattern corresponding to the position is detected. Since the signals are updated one after another and input to the movable element, there is no deterioration in the image quality during the reproduction, and the magnetic tapes having different recording levels can follow the change over time in the track bend, and thus can be improved. A reproduced image can be obtained.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First
In the figure, the reproduction output of the magnetic head (1) is
Amplified in 4), input to the detector (25), where it is envelope-detected, input to the A / D converter (26) and converted to a digital signal. The output of the A / D converter (26) is input to an input / output circuit (28) of a microcomputer (33). Where the A / D converter (26)
Input / output circuit for sampling timing signal (28)
Output more. The output of a reproduction mode signal generator (22) for outputting a signal (hereinafter, referred to as PB) indicating whether or not the apparatus is in the reproduction mode is also input to the input / output circuit (28). Here, it is assumed that the reproduction mode signal is output from the reproduction mode signal generator (22) when the signal is at the high level (hereinafter, referred to as H) and at the low level (hereinafter, referred to as L) at other times. The output of the field signal generator that generates a signal (hereinafter, referred to as FD) that changes on a field basis is also input to the input / output circuit (28) of the microcomputer (33). Here, it is assumed that H is a field to be reproduced by the magnetic head (1), and L is outputted from the field signal generator (23) otherwise. The signal output from the input / output circuit (28) is converted to an analog signal by the D / A converter (21) and then applied to the movable element (2) amplified by the amplifier (20). The microcomputer (33) consists of a reproduction mode signal generator (22), a field signal generator (23), and an A / D converter (2
Input / output circuit (28) for inputting the signal from 6) and outputting the signal to D / A converter (21) and A / D converter (26) and data memory (29) for temporarily storing data And an arithmetic circuit (30) for performing an operation, a program memory (31) for controlling an operation, and a timer (32) for measuring time.

 Next, the operation will be described.

In FIG. 2A, when the track recorded on the magnetic tape (4) is (34a), first, the magnetic head (1)
Is output from the input / output circuit (28), converted into an analog signal by the D / A converter (21), amplified by the amplifier (20), and applied to the movable element (2). The output of the detector (25) at this time is as shown in FIG. 2 (c). Also, it has been experimentally confirmed that no significant deterioration in image quality is observed even when the magnetic head (1) is moved in the track width or the width direction of the magnetic tape within a range of 1/3 or less of the track width. As shown in FIG. 7, when a track is recorded on the magnetic tape (4), the width indicated by TP is set as the track pitch with respect to the track width TW, and if there is no guard band, TW and TP match. Will be.

Here, the moving amount in the present embodiment is set to ± a (range ±
The output signal from the input / output circuit (28) corresponding to a to the D / A converter (21) is ± A). Then, the magnetic head (1)
V + A and V + V at the positions of v + a and v−a
Similarly, -A is output from the input / output circuit (28) to the D / A converter (21). At that time, the outputs of the detectors (25)
2B and 2D. The signals shown in FIGS. 2B, 2C and 2D are applied to the timer (32).
A / D converter (26) through the input / output circuit (28)
The digital signal is converted by the A / D converter (26) at the timing of T0 to T9 according to the sampling signal input to the memory, and is stored in the data memory (29) via the input / output circuit (28).
Next, at each time from T0 to T9, v + a, v, v−
The arithmetic circuit (30) calculates which position of the magnetic head (1) has the maximum envelope detection signal output from the detector (25) when the magnetic head (1) is located in the data memory (29). I do. Then, at time Tk (k = 0 to 9), the signal (v
+ A for V + A, V for v, V for v-a
-A) at the timing of Tk '(k = 0 to 9) measured by the timer (32) from the input / output circuit (28).
Output to 1). The signal pattern output from the input / output circuit (28) at that time is shown by the solid line in FIG. A / D
Tk ≧ Tk ′ in consideration of the delay of the sample and hold in the converter (26) and other circuits, the response time of the movable element (2), etc.
It is necessary to FIG. 4 (b) shows the detection signal output from the detector (25) at this time. The detected signal shown in FIG. 4 (b) is again converted to an A / D converter (2
The data is sampled by 6) and stored in the data memory (29) via the input / output circuit (28).

Then, first, the signal pattern of FIG. 4A is changed by + A and the offset level as shown by the upward arrow in the state as it is. That is, VA is V,
The V portion is changed to V + A, and the V + A portion is changed to V + 2A. Then, the output of the detector (25) at that time is sampled by the A / D converter (26) at timings T0 to T9 and stored in the data memory (29) via the input / output circuit (28). Similarly, the output of the detector (25) when the offset level is changed by -A shown in the signal pattern of FIG. 4A in the downward direction of the arrow is also stored in the data memory (29). The arithmetic circuit (30) performs the above three cases (the pattern of FIG. 4 (a), which is changed by + A or -A) at the respective times T0 to T9 from the data of the data memory (29). In this case, the maximum value is detected, and the output signal at that time is output from the input / output circuit (28) to the D / A converter (21) at timings T0 'to T9'. The output signal pattern is shown in FIG. The detected signal from the detector (25) at this time is shown in FIG. 4 (d), and it can be seen that a good reproduced signal can be obtained even for a curved track as indicated by 34a in FIG. 2 (a). After this, even if the above operation is repeated, the signal output from the input / output circuit (28) to the D / A converter (21) is the signal pattern shown in FIG. , And the output of the detector (25) remains as shown in FIG. 4 (d), and a good reproduced signal is held. Further, even with a magnetic tape recorded by the same magnetic recording device, there is a time-dependent change in track bend due to expansion and contraction of the magnetic tape and a change in tension of the reproducing device. It is also possible to maintain a good reproduction output by repeating the above operation according to the present invention. For example, when the track bend changes from 34a in FIG. 2 (a) to 34b in FIG. 5 (a) due to aging, the signal pattern shown by the solid line in FIG. The offset level is changed by ± A in the up and down direction indicated by, and in each case of T0 to T9, it is detected in which case the maximum is detected,
The output signal at that time is output from the input / output circuit (28) to the D / A converter (21) at timings T0 'to T9'. The output signal pattern at this time is a solid line in FIG. 5 (b), and the detection signal from the detector (25) at this time is as shown in FIG. 5 (c). It can be seen that the reproduced signal is retained.

 Next, the operation will be described with reference to the flowchart of FIG.

First, in (100), it is detected whether or not the mode is the reproduction mode. If the mode is the reproduction mode, the process proceeds to (101). In (101), in the data memory (29) where addresses are set as shown in FIG.
VA at addresses 00 to O09, V, O20 at addresses O10 to O19
Data of V + A is input to addresses ~ O29. Next, in (102), 0 is stored at the address X in the data memory (29). And the rise of FD at (103),
That is, the magnetic head (1) detects whether or not a track to be reproduced has arrived. If a rise is detected, the process proceeds to (104).

Next, after resetting the timer (32) in (104), the timer (32) is started and time measurement is started. And
In (105), 0 is stored in the address Y in the data memory (29). Next, wait until the time reaches T0 'in (106),
When it becomes 0 ', the value VA previously stored in O00 is output from the data memory (29) to the D / A converter (21) via the input / output circuit (28) at (107), and (108) ), Wait until time T0, and when it reaches T0, convert the sampling signal to an A / D converter (2
6) outputs the sampled data to the input / output circuit (2
The data is stored at address I00 in the data memory (29) via 8). Next, in step (110), 1 is added to the content of the address Y to obtain 1.
Since the content of the address Y is not 10 in (111), the process returns to (106).
Hereinafter, similarly, the operations from (106) to (111) are repeated until the content of the address Y becomes 10. By this, O01 ~ O
This means that the data VA output at the address 09 and sampled at the timings T1 to T9 are stored at the addresses I10 to I19. Next, at step (113), 1 is added to the content of address X to 1; at step (113), the content of address X is not 3, so (102)
And the operations from (103) to (113) are repeated until the content of the address X becomes 3. As a result, V which is the content of the addresses O10 to O19 is output, and the data sampled at the timings T1 to T9 is stored in the addresses I10 to I19.
This means that V + A, which is the contents of addresses .about.O29, is output, and data sampled at timings T1 to T9 is stored in addresses I20 to I29. That is, FIGS. 2 (b), (c),
This means that the signal of (d) is sampled and stored in the data memory (29).

Next, at (114), 0 is stored in the address Y. And (11
In step 5), when the maximum of the contents of the addresses I 00, I 10 and I 20 is found, the corresponding OMAX Y is found. In other words, if the address I00 is the maximum, O00 is set, if the address I10 is the maximum, O10 is set. Then at (116) (OMAX Y
-A) is stored at address O00, OMAX Y is stored at O10, and (OMAX Y + A) is stored at O2.
Store it at address 0. Next, in step (117), 1 is added to the contents of the address Y to obtain 1; in step (118), the contents of the address Y are not 10, so (1)
Return to 15). In the same manner, the operations from (115) to (118) are repeated until the content of the address Y becomes 10. As a result, the D / A converter (21) corresponding to when the input signal from the A / D converter (26) becomes maximum at each time of T0 to T9
Is stored at addresses O10 to O19, and a signal obtained by offsetting the above level by -A and + A is output to O00 to O19.
This means that it is stored at addresses O09 and O20 to O29.
That is, the data for the signal pattern indicated by the solid line in FIG. 4A is stored at addresses O10 to O19.

Next, in step (119), the CPU waits until the FD rises again, that is, until the next track to be reproduced comes. If the rise of the FD is detected, the timer (32) is reset and started at (120), and the time measurement is started. Then (12
In step 1), 0 is stored in the address Y. And at (122) the time is T
Wait until it reaches 0 ', and when it reaches T0', the contents of address O10 are output from the input / output circuit (28) to the D / A converter (21) at (123). Then, at (124), 1 is added to the content of the address Y to obtain 1. Next, since the content of the address Y is not 10 in (125), (12
Returning to 2), the operations from (122) to (125) are repeated until the content of the address Y becomes 10. Thereby, FIG. 4 (a)
Signal pattern from the input / output circuit (28) to the D / A converter (2
Output to 1). Next, if PB is H in (126), the process returns to (102), but if L, the mode is other than the reproduction mode, so that the next process is performed. When PB returns to (102) with H, the operations from (102) to (113) are repeated again until the content of the address X becomes 3. This gives (11
O10 obtained by repeating the operations from 4) to (118)
The output signal pattern data stored at addresses ~ O19 and O00 obtained by offsetting the data by -A and + A.
A / D converter (2) when three signal patterns of data stored at addresses 0 to O09 and O20 to O29 are given.
The input signal data from 6) are respectively transferred at the timings T0 to T9 at the addresses I10 to I19, I00 to I09, and I20 to I9.
Remember at address 29. Then, from (114) to (11
A new signal pattern is found by the operations up to 8) and stored in addresses O10 to O19, and this is stored in the input / output circuit (28) by repeating the operations from (119) to (125).
To the D / A converter (21). The output pattern is the pattern shown by the solid line in FIG.

The operation described above is performed until PB becomes L in (126).
That is, the operation is repeated during the reproduction mode. Generally speaking, three patterns of a signal pattern which is a repetitive operation from (102) to (113) and a pattern obtained by offsetting the signal pattern by ± A are output, and A / A in each case is output.
The input data from the D converter (26) is stored in the data memory (29), and the best new pattern is stored in the data memory (29).
4) through (118) to find out,
The new pattern is output from the input / output circuit (28) to the D / A converter (21) by repeating the operations from (119) to (125), and if PB is H in (126), the process returns to (102). Will be repeated again.

In the above embodiment, the output from the input / output circuit (28) is
The signal converted to analog by the D / A converter (21) and applied to the movable element (2) via the amplifier (20) changes in a step-like manner. Considering the signal patterns shown in FIGS. 4 (a) and (c) and FIG. 5 (b) as a signal connected by a smooth curve,
The detected signals shown in (b), (d) and FIG. 5 (c) also have a smooth shape instead of a sawtooth waveform. Further, in the above embodiment, the microcomputer is used, but it may be constituted by hardware instead. If the change in the detected signal near the entrance of the track is large, OX0 of the processing of (107) and (123) is used.
The contents of the address and the address O10 may be output to the D / A converter (21) immediately before (103) and (119). If the track curve changes slowly over time, (119) to (1
The operation of outputting the new pattern up to 25) may be repeated for a certain period to extend the interval at which the pattern is updated. Also, in (101), fixed signals are given to addresses O00 to O09, O10 to O19, and O20 to O29, respectively.
This is not limited to a constant signal, but may be any signal pattern suitable for a magnetic recording / reproducing operation to which the present invention is applied.

[Effects of the Invention] As described above, according to the present invention, the magnetic head is moved within a predetermined range in the track width or the width direction of the magnetic tape, and the position of the magnetic head at which the reproduction signal becomes maximum within the movement range is detected. Since the pattern signal is updated one after another and input to the movable element, it follows the change over time of the track curve without deteriorating the image quality during the playback of the recording, and always provides a high-quality good reproduced image. Can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a device used in the present invention, FIG. 2 is an explanatory diagram showing a recorded track and a state of a reproduced envelope detection signal, and FIG. 3 shows addresses of memories in a data memory. FIG. 4 is a diagram showing an output signal pattern from a microcomputer and an envelope detection signal, and FIG.
The figure shows a track when the track bend changes with time, the output signal pattern from the microcomputer and the envelope detection signal at that time, FIG. 6 is a flowchart showing the operation of the present invention, and FIG. 7 explains the track pitch. 8, FIG. 8 is a diagram showing a magnetic head mounted state, FIG. 9 is a block diagram showing a conventional magnetic recording / reproducing apparatus, FIG. 10 is an operation waveform diagram thereof, and FIG. FIG. 12 is a diagram showing the method, FIG. 12 is a diagram showing the output waveform of the head at that time, FIG.
The figure shows an example of track bending stored in the memory. DESCRIPTION OF SYMBOLS 1 ... Magnetic head, 2 ... Movable element, 20,24 ... Amplifier, 21 ... D / A converter, 22 ... Reproduction mode signal generator, 2
3 ... Yield signal generator, 25 ... Detector, 26 ... A / D converter, 28 ... I / O circuit, 29 ... Data memory, 30 ...
Arithmetic circuit, 31... Program memory, 32... Timer In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] A magnetic head is mounted on a movable element, and an input signal such as electricity is externally applied to the movable element.
In a method of performing magnetic recording and reproduction using a magnetic recording and reproducing apparatus that moves and tracks a magnetic head to a track written on a magnetic tape, a predetermined first pattern such that a locus of the magnetic head becomes a first pattern Applying a signal to a movable element, and keeping the first pattern as it is, for a track different from the track that output the first pattern signal, the magnetic head has a track width in a range of 1/3 or less of a track pitch. In the direction, read the reproduction signal at that time, detect the position of the magnetic head where the reproduction signal is maximum in the movement range, the second pattern signal required to move the magnetic head to that position And a track different from the track from which the first and second pattern signals were output while leaving the second pattern as it is. The magnetic head is moved in the track width direction in a range of 1/3 or less of the track pitch with respect to the track pitch, a read signal at that time is read, and a position of the magnetic head at which the read signal is maximized within the moving range is detected. Inputting a third pattern signal required for moving the magnetic head to the position to the movable element.