JPH09128914A - Tracking controller and magnetic recording/reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the malfunction due to the detection of inversed lock state and also to speed up the tracking by performing the tracking control in the manner of selecting the signal, which is set up by adding/subtracting the tracking error signals obtained from a magnetic head simultaneously traveling on both adjacent tracks, in accordance with the level of error signal. SOLUTION: By latch circuits 131, 132 for the tracking error signal, digital difference signals are latched as the error signals with sampling timings (a), (c) and (b), and both signals are added/subtracted by an adder 133 and subtracter 134 and outputted to error signal latch circuits 135, 136. At this stage, the waveforms are rectified in a Schmitt device 137, and the signals are binarized by the reference level and discriminated by a selecting/discriminating part 138, then changed over to 1st-4th error signals by a selection device 125. That is, the tracking control is carried out by using the 1st error signal when the tracking deviation is within ±1 track and by using the 2nd or 3rd error signal when the deviation is >=±1 track. By this procedure, the tracking is quickly set into the normal lock position even in the case of inversed lock position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking control device for performing tracking control of a reproducing head using a pilot signal and a magnetic recording / reproducing device equipped with this tracking control device.

[0002]

2. Description of the Related Art Among conventional magnetic recording / reproducing devices, there is a model for performing tracking control using a pilot signal of two frequencies, and the tracking control will be described below. FIG. 10 shows the mounting positions of the four magnetic heads on the rotary cylinder mounted in the above-mentioned magnetic recording / reproducing apparatus. A1 and B1, and A2 and B2 are double azimuth heads, respectively, which surround the rotary cylinder 30. At 18
It is attached facing 0 degrees. + And-in the figure indicate the azimuth angle of the head. During recording, the A1 head and the B1 head simultaneously record a track, the A1 head records an f0 track that does not contain a pilot signal, and the B1 head records a track that contains an f1 pilot signal. When the rotary cylinder 30 rotates 180 degrees, A2 head and B
2 heads simultaneously record tracks, A2 head contains f0 track containing no pilot signal, B2 head contains f2 track
Record the track containing the pilot signal.

FIG. 11 shows a track pattern recorded on a magnetic recording tape by the above-mentioned 4 heads. That is, the track circulation is f0, f1, f0, and f2 every four tracks. During playback, A1 and A2 heads are f0
When a track is traced, the A1 and A2 head outputs reproduce the f1 and f2 pilot signals from adjacent tracks on the left and right as crosstalk components, and detect the tracking deviation amount of each head by comparing the levels of f1 and f2. can do.

FIG. 12 is a diagram showing an example of the configuration of a conventional tracking control device mounted on a conventional magnetic recording / reproducing device. The signals reproduced by the heads A1, B1 and the heads A2, B2 are amplified by the reproduction amplifiers 1.1, 1.2, 1.3, 1.4 and reproduced by the head switching devices 2, 3 and the reproduction signal switching device 4. The signal is selected and the band pass filter (BP
F) Input to 5. The bandpass filter 5 extracts a pilot signal band from the input reproduction signal, amplifies it by an amplifier 6, and outputs it to a BPF 7 having a center frequency of f1 and a BPF 8 having a center frequency of f2.

The BPFs 7 and 8 receive f1 from the input signal, respectively.
The f1 pilot signal of the frequency and the f2 pilot signal of the f2 frequency are extracted, input to the detectors 9 and 10, and level-detected to be a DC voltage. The two level-detected DC voltages are input to the + terminal and the-terminal of the comparator 11, and the difference of (f2 pilot signal level-f1 pilot signal level) is obtained in this comparator 11. The difference output from the comparator 11 is input to an A / D converter 121 of a microcomputer (hereinafter abbreviated as a microcomputer) 12 to be A / D converted and thereafter processed as a digital value.

The A / D conversion timing of the A / D converter 121 is determined by the timing signal output from the timing pulse generation circuit 130 in the microcomputer 12. The difference (digital value) output from the A / D converter 121 is input to the subtractor 122, and the reference value 50 is subtracted. The reference value 50 is a value obtained by A / D converting the level output by the comparator 11 when "f1 pilot signal level = f2 pilot signal level". Therefore, the output of the subtractor 122 is "f1 pilot signal level =
"2" at "f2 pilot signal level",
When "f1 pilot signal level <f2 pilot signal level", "positive value": "f1 pilot signal level>"
At the “f2 pilot signal level”, it becomes a “negative value”.

The output of the subtractor 122 is input to one end of the polarity switch 124 and the other end of the polarity switch 124 through the polarity inverter 123. The polarity switch 124 selects a signal by switching each terminal so as to switch the polarity of the subtractor output to the selector 125 when the A1 head scans the track and when the A2 head scans the track. To do. This is because the left adjacent track is f when the A1 head is scanned.
In the 2 tracks, the right adjacent is the f1 track,
This is because the relationship is reversed when the A2 head is scanned.
The output of the polarity switcher 124 becomes a tracking error signal and is input to the selector 125. When the selector 125 is switched to the terminal L side at the timings a and c described later, it is obtained from the terminal L side. The tracking error signal is added to a capstan velocity error (not shown) and is input to the rotation phase control system of the capstan motor for tracking control.

FIG. 13 is a diagram showing the relationship between the tracking deviation amount of the A1 head and the tracking error signal. A1
When the head scans the center of the T4 track, "f
1 pilot signal level = f2 pilot signal level "
Therefore, the tracking error signal (error value) becomes 0, but when the A1 head shifts in the direction of the adjacent T5 (f1) track to the right, the tracking error value becomes a negative value, and the capstan is decelerated and the head is decelerated. Of the A1 head moves to the left adjacent to T3 (f2).
When it is deviated in the track direction, the tracking error value becomes a positive value and the capstan is accelerated to move the head scanning to the right.

Here, the magnitude of the tracking error value increases with respect to the tracking deviation amount in proportion to the deviation amount up to one track, but decreases when exceeding the deviation amount of one track, and decreases with the deviation amount of two tracks. The value becomes "0", and it does not try to move to the left or right, and it becomes a stable state at first glance. Moreover, since the azimuth of the head and the azimuth of the track match, the main signal can be reproduced correctly.

However, even if the tracking error value is "0", the position of this two-track shift is not a stable point of tracking, and if the head scan moves left or right even a little, the error value will try to move left and right in the same direction. Eventually, it will cross the reverse azimuth track and pull into the regular tracking position. Here, a state in which the tracking error value of this two-track deviation is "0" and tracking is stable (locked) at that position for a while is called a back lock state. Therefore, once the back lock state is reached, it takes a considerable time to pull the scanning of the head to the regular lock position, and sometimes it takes 1 to 3 seconds.

A conventional solution to the above problem in the related art will be described below. FIG. 14 is a diagram showing the relationship between the tracking deviation amount of the B1 head and the tracking error signal. When the A1 head scans the center of the T4 track and the tracking is locked at the normal position, the B1 head scans the center of the T5 track. At this time, as the pilot signal reproduced by the B1 head, only the f1 pilot signal is reproduced at a large level. Therefore, the tracking error value (pilot signal level of f2−pilot signal level of f1) exhibits a negative maximum value. When the B1 head shifts to the left and right adjacent tracks, the tracking error value changes as shown in FIG. Therefore, as shown in the configuration diagram of FIG. 12, the tracking error value obtained from the B1 head is passed through the Schmitt device 126,
For example, at the Schmidt level shown in FIG. 14, "1", "0"
Is binarized. According to FIG. 14, the binarized value is "1".
When it is, the tracking is in the back lock state, and when it is "0", it can be determined that it is in the normal lock position or in the middle of pulling.

FIG. 16 is a timing chart showing signals input to and output from the functional blocks shown in FIG. 12 when the tracking is pulled to the normal lock position. FIG. 17 is a timing chart showing signals of each block when the tracking is at the back lock position. 16A and FIG.
The head switching pulse shown in FIG. 7A is output from the timing pulse generation circuit 130 and 180
It is a signal for selecting A1 head / B1 head or A2 head / B2 head that are facing each other. FIG. 16 (B),
Reference numeral 17 (B) is a signal for switching the reproduction signal, which is output from the timing pulse generation circuit 130 for the reproduction signal switching pulse and is input to the tracking control circuit, and selects the B1 or B2 head output near the center of the track.

The A / D converter 121 in the microcomputer 12 is
For example, the output signal of the comparator 11 is sampled at the timings a, b, and c in FIGS. 16N and 17N, and the tracking error values processed at the timings a and c are selected by the selector 125. Tracking control is performed by switching to the terminal L at the timings of c and c. Here, the output waveform of the polarity reversing device 123 shown in FIGS. 16 (K) and 17 (K) and the output waveform of the polarity switching device 124 shown in FIGS. 16 (M) and 17 (M) are for convenience of description. The waveforms when the A / D conversion is sequentially performed are shown in FIG. Next, the value sampled at the b timing by the A / D converter 121 is processed by the subtractor 122 and the polarity switcher 124, and then selected by the selector 125 to be input to the Schmitt device 126. Or a value of “0” is input to the back lock determination unit 127.

In FIG. 16, since the tracking is at the regular lock position, the Schmitt device 1 as shown in FIG.
The output of 26 is always "0", and the output of the Schmitt device 126 is "1" as shown in Fig. 17 (O) because it is the back lock position in Fig. 17 (O). The back lock determination unit 127 determines the input from the Schmitt device 126 as described below. That is, although the back lock is shown when the input is "1", this "1" is in the center of the back lock position, is on the verge of shifting to "0", or malfunction due to noise. Usually "1" to determine if
See the continuity of. For example, the back lock is determined only when the number becomes “1” for four consecutive tracks.

When the back lock discriminating unit 127 determines that the back lock is applied, the polarity of the switching control terminal of the selector 128 is reversed. That is, if the selector 128 has been used to select the terminal "L" side, the terminal is switched to the terminal "H" side by the back lock detection. The head switching timing and a signal obtained by inverting the signal are input to the selector 128, and the output of the selector 128 becomes the inverted signal up to now due to the back lock detection.

The output of the selector 128 is input to the control terminal of the polarity switch 124, and the polarity of the output of the subtractor 122 is inverted. As shown in FIG. 17 (P), by inverting the control terminal of the polarity switch 124, the output of the polarity switch 124 becomes a waveform pulled to the regular lock position as shown in FIG. 17 (Q), and the Schmitt output Also becomes "0" as shown in FIG.

The above operation will be described with reference to FIG. 15. When the A1 head scans the T6 track and the back lock determination unit 127 detects the back lock, the output of the polarity switch 124 is inverted. Inverting the polarity of the polarity switch 124 means inverting the positive / negative of the signal.
The tracking error value shown by the solid line is obtained. Therefore, after the back lock is detected, the tracking error in the T6 track has a downward slope to the right, and the track is in the normal lock position. That is, it is possible to immediately pull in the regular lock position from the back lock position without crossing the reverse azimuth track.

However, the method of canceling the back lock state and retracting it to the regular lock position by the above method has the following problems. First, in order to prevent a malfunction of the back lock detection, it is necessary to check the continuity of the back lock detection signal, and it takes time to make the determination. In addition, when the user moves from the back lock position and loses the back lock while watching the continuity, the pull-in time to the regular lock becomes long. Further, after the back lock is detected and the selected polarity of the polarity switch 124 is inverted, the tracking becomes unstable until the tracking is pulled in. Therefore, it is necessary to stop the back lock detection operation (1 to 2 seconds). Further, in the case of a four-head system, after the back lock is detected, the track recorded by the A2 / B2 head is reproduced by the A1 / B1 head, and therefore the level of the reproduction signal may be lowered due to the mounting step of the head or the like. .

[0019]

As described above, in the conventional tracking control device, it is necessary to check the continuity of the back lock detection signal in order to prevent malfunction of the back lock detection, and it takes time to make the judgment. I will end up. In addition, when the user moves from the back lock position and loses the back lock while watching the continuity, the pull-in time to the regular lock becomes long. Also, after detecting the back lock and inverting the polarity reversing device,
It is also necessary to stop the back lock detection operation for a while until the tracking is pulled in. Further, in the case of a 4-head system, since the track recorded by the A2 / B2 head is reproduced by the A1 / B1 head after the back lock is detected, the level of the reproduction signal may be lowered due to a step of mounting the head or the like.

Therefore, the present invention has been made to solve the above problems, and tracking can always be quickly pulled into the normal lock state without reversing the back lock state to the normal lock state. An object of the present invention is to provide a tracking control device and a magnetic recording / reproducing device using the tracking control device.

[0021]

According to a first aspect of the present invention, there is provided a magnetic tape in which a plurality of pilot signals having different frequencies are cyclically recorded on a track-by-track basis with unit tracks having no pilot signal interposed therebetween. Reproduction means for driving and reproducing the pilot signals recorded on the magnetic tape by the first and second rotary magnetic heads for simultaneously scanning two tracks respectively, and for reproducing by the first rotary magnetic head for scanning the tracks. A signal reproduced by a first signal generating means for obtaining a first tracking error signal from a pilot signal included in the signal and a second rotary magnetic head for scanning an adjacent track scanned by the first rotary magnetic head. By a second signal creating means for obtaining a second tracking error signal from a pilot signal included in And it made a first tracking error signal and the second tracking error signal and adding means for adding created by the second signal generating means, said first
Subtracting means for subtracting the second tracking error signal created by the second signal creating means from the first tracking error signal created by the signal creating means, and the third tracking obtained by the adding means. Error signal,
Alternatively, either one of the fourth tracking error signal obtained from the output of the subtracting means or the first tracking error signal produced by the first signal producing means is selected to select the signal. A selection unit that uses the original tracking error signal used to control the running phase of the magnetic tape,
Which one of the selecting means based on the level of the first tracking error signal created by the first signal creating means and the level of the second tracking error signal created by the second signal creating means. And a determining means for determining whether or not to select the tracking error signal.

According to a second aspect of the present invention, a plurality of pilot signals having different frequencies are cyclically recorded on a track-by-track basis with a unit track having no pilot signal interposed therebetween, and the magnetic tape is run and driven. Reproducing means for reproducing the pilot signals recorded on the tape by the first and second rotary magnetic heads for simultaneously scanning two tracks respectively, and the pilot signal included in the signal reproduced by the first rotary magnetic head for scanning the tracks. From the pilot signal included in the signal reproduced by the first signal generating means for obtaining the first tracking error signal from the first rotary magnetic head and the signal reproduced by the second rotary magnetic head scanning the adjacent track scanned by the first rotary magnetic head. Second signal creating means for obtaining a second tracking error signal, and a third signal having a preset value
Tracking error signal output means for outputting the tracking error signal, the fourth tracking error signal output means for outputting the fourth tracking error signal having a preset value, and the third tracking error signal A third tracking error signal output from the output means,
Alternatively, either one of the fourth tracking error signal output from the fourth tracking error signal output means or the first tracking error signal generated by the first signal generating means is output. Selection means for selecting the original tracking error signal to be used for controlling the running phase of the magnetic tape, the level of the first tracking error signal created by the first signal creating means, and the second signal creation The determining means determines the tracking error signal to be selected by the selecting means based on the level of the second tracking error signal created by the means.

According to a third aspect of the present invention, a plurality of pilot signals having different frequencies are cyclically recorded on a track-by-track basis with a unit track between which pilot signals do not exist sandwiched between two pilot signals. Reproducing means for reproducing the pilot signals recorded on the tape by the first and second rotary magnetic heads for scanning one track, respectively.
First signal generating means for obtaining a first tracking error signal by a pilot signal included in a signal reproduced by a first rotary magnetic head for scanning a track;
Second signal generating means for obtaining a second tracking error signal from a pilot signal included in a signal reproduced by a second rotary magnetic head which scans an adjacent track scanned by the rotary magnetic head of (1), Addition means for adding the first tracking error signal created by the signal creation means and the second tracking error signal created by the second signal creation means, and the addition means created by the first signal creation means From the first tracking error signal to the second
Subtracting means for subtracting the second tracking error signal generated by the signal generating means, and the third tracking error signal obtained from the adding means, or the fourth tracking error signal obtained from the output of the subtracting means. Or selecting any one of the first tracking error signals created by the first signal creating means to be the original tracking error signal used for controlling the running phase of the magnetic tape. Means, and the selection based on the level of the first tracking error signal created by the first signal creating means and the level of the second tracking error signal created by the second signal creating means. And a determining means for determining which tracking error signal should be selected by the means.

According to a fourth aspect of the present invention, a plurality of pilot signals having different frequencies are cyclically recorded on a track-by-track basis with a unit track having no pilot signal sandwiched therebetween, and the magnetic tape is driven. Reproducing means for reproducing the pilot signals recorded on the tape by the first and second rotary magnetic heads for scanning one track, respectively.
First signal generating means for obtaining a first tracking error signal from a pilot signal included in a signal reproduced by a first rotary magnetic head for scanning a track, and an adjacent track scanned by the first rotary magnetic head. Second to scan
A second tracking error signal from a pilot signal included in the signal reproduced by the rotating magnetic head
Signal producing means, a third tracking error signal output means for outputting a third tracking error signal having a preset value, and a fourth tracking error signal for outputting a fourth tracking error signal having a preset value. Tracking error signal output means and the third tracking error signal output from the third tracking error signal output means, or the fourth tracking error signal output from the fourth tracking error signal output means. , Or selecting means for selecting any one of the first tracking error signals created by the first signal creating means as the original tracking error signal used for controlling the running phase of the magnetic tape. And the level of the first tracking error signal created by the first signal creating means and the second signal creating procedure. And a structure in which and a determination means for performing determination of whether to select one of a tracking error signal by the selection means based on the level of the created second tracking error signal by.

According to a fifth aspect of the present invention, there is provided a third tracking error signal output from the third tracking error signal output means and a fourth tracking error signal output from the fourth tracking error signal output means. The polarities are opposite to each other.

According to a sixth aspect of the present invention, there is provided a third tracking error signal output from the third tracking error signal output means and a fourth tracking error signal output from the fourth tracking error signal output means. The polarities are the same.

According to a seventh aspect of the present invention, the judging means for judging the selection of the selecting means by the level of the second tracking error signal and the level of the first tracking error signal is a predetermined tracking error signal. Compare by value 2
The first binary discriminating means for discriminating into a value and the second discriminating means for discriminating into a binary value by comparing the second tracking error signal with a predetermined value.
Value discriminating means, and when the second binary discriminating means shows the first value, the first tracking error signal is selected, and the second binary discriminating means shows the second value. In this case, either the third tracking error signal or the fourth tracking error signal is determined depending on whether the value indicated by the first binary discriminating means is the first value or the second value. It is provided with a configuration for selecting one.

According to an eighth aspect of the present invention, there is provided a magnetic recording / reproducing apparatus for recording / reproducing information on / from a magnetic tape by a plurality of magnetic heads on a rotary cylinder. There is provided a configuration for performing tracking control between the reproducing magnetic head and the tracks on the magnetic tape.

[0029]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a first embodiment of a tracking control device mounted on a magnetic recording / reproducing device of the present invention. A1, B1, A2,
B2 is a head for scanning and reproducing a tape (not shown),
1.1 is a reproduction amplifier for amplifying the reproduction signal of the A1 head,
1.2 is a reproduction amplifier for amplifying the reproduction signal of the B1 head,
1.3 is a reproduction amplifier for amplifying the reproduction signal of the A2 head,
1.4 is a reproduction amplifier for amplifying the reproduction signal of the B2 head,
Reference numeral 2 is a head switch that alternately outputs the outputs of the reproduction amplifiers 1.1 and 1.3, and 3 is reproduction amplifiers 1.2 and 1.
Head switching device that alternately outputs 4 outputs, 4
Is a reproduction signal switcher for alternately switching and outputting the outputs of the head switches 2, 3, and 5 is a band pass filter (BPF) 6 for passing only the pilot signal band of the reproduction signal output from the reproduction signal switcher 6, Is the bandpass filter 5
An amplifier for amplifying the level of the pilot signal extracted by, 7 is a bandpass filter whose center frequency is f1, and 8
Is a bandpass filter with a center frequency of f2, 9 is a detector that detects a pilot signal with a frequency of f1, 10 is a detector that detects a pilot signal with a frequency of f2, and 11 is a difference between the detection signals of the detectors 9 and 10. , 12 is a microcomputer for creating a tracking error signal,
A main signal processing unit 13 processes a main signal such as a video signal reproduced by the A1, B1, A2 and B2 heads.

Here, in the microcomputer 12, an A / D converter 121 for converting the differential signal input from the comparator 11 into a digital signal, and a reference value from the differential signal output from the A / D converter 121. A subtractor 122 that subtracts 50, a polarity inverter 123 that inverts the polarity of the subtraction signal output from the subtractor 122, a polarity switcher 124 that switches the polarity of the subtraction signal output from the subtractor 122 to a tracking error signal, A selector 125 for selecting any one of the tracking error signals output from the first, third, and fourth tracking error signal latch circuits 131, 135, 136 as an original tracking error signal, a head switching pulse, and a reproduction signal. Timing pulse generating circuit 130 for generating switching pulse and sampling pulse at A / D conversion, polarity First tracking error signal latch circuit 131 for latching the tracking error signal output from the replacement unit 124 sampling timing a, with c,
A second tracking error signal latch circuit 132 that latches the tracking error signal output from the polarity switch 124 at the sampling timing b, and a second tracking error signal latched by the first tracking error signal latch circuit 131 Adder 133 for adding the second tracking error signal latched by the tracking error signal latch circuit 132, and the second tracking error signal from the first tracking error signal latched by the first tracking error signal latch circuit 131. A subtracter 134 for subtracting the second tracking error signal latched by the latch circuit 132, and a third tracking error signal latch circuit 1 for latching the added value of the adder 133.
35, a fourth tracking error signal latch circuit 136 that latches the subtracted value of the subtractor 134, and a Schmitt device that binarizes the tracking error signal latched by the first or second tracking error signal latch circuit to shape the waveform. 137, the selector 1 based on the waveform shaping value of the first or second tracking error signal input from the Schmitt device 137.
A selector discriminating unit 138 for discriminating the type of the tracking signal selected and output at 25 is formed.

Next, the operation of this embodiment will be described. The signals reproduced by the head A1, head B1, head A2, and head B2 are reproduction amplifiers 1.1, 1.2, 1.3, 1.4.
Is amplified by the head switching devices 2 and 3 and the reproduction signal switching device 4
The reproduction signal is selected by the band pass filter (BP
F) Input to 5. The band pass filter 5 extracts a pilot band from the input pilot signal, amplifies the pilot band by the amplifier 6, and outputs the B.B. P.
F7 and B.2 having a center frequency of f2. P. Output to F8.

The BPFs 7 and 8 receive f1 from the input signal, respectively.
In order to extract the f1 pilot signal of the frequency and the f2 pilot signal of the f2 frequency and output them to the detectors 9 and 10,
The f1 and f2 pilot signals are level-detected by the detectors 9 and 10 to be a DC voltage. Since the two DC voltages thus obtained are input to the + terminal and the-terminal of the comparator 11, the comparator 11 obtains the difference of (f2 pilot signal level-f1 pilot signal level). The difference output from the comparator 11 is input to an A / D converter 121 of a microcomputer (hereinafter abbreviated as a microcomputer) 12 to be A / D converted and thereafter processed as a digital value.

The A / D conversion timing of the A / D converter 121 is determined by the timing signals a, b and c shown in FIG. 2 (N) output from the timing pulse generation circuit 130 in the microcomputer 12. . A / D converter 121
The difference (digital value) output from the subtracter 122
, The reference value 50 is subtracted. Subtractor 1
The output of 22 is input directly to one end of the polarity switch 124 or to the other end of the polarity switch 124 through the polarity inverter 123. The polarity switcher 124 switches the polarity of the subtraction value output from the subtractor 122 between when the A1 head scans the track and when the A2 head scans the track. This is because the left adjacent track is the f2 track and the right adjacent track is the f1 track when the A1 head is scanned, but the relationship is reversed when the A2 head is scanned. The output of the polarity switch 124 is output to the first tracking error signal latch circuit 131 and the second tracking error signal latch circuit 132.

Here, the A / D converter 121 outputs the timing pulse generating circuit 130 at the sampling timings a, b, and c shown in FIG. The differential signal as shown is sampled and converted into a digital signal. Therefore, at the sampling timings a and c, the A / D signal is output from the polarity switch 124.
The difference signal converted into a digital value by the converter 121 at the sampling timings a and c is output, and the difference signal converted into a digital value by the A / D converter 121 at the sampling timing b is output at the sampling timing b. .

Therefore, the first tracking error signal latch circuit 131 latches the differential signal converted into the digital value by the A / D converter 121 at the sampling timings a and c as the first tracking error signal, and the second tracking error signal. The tracking error signal latch circuit 132 latches the differential signal converted into a digital value at the sampling timing b by the A / D converter 121 as a second tracking error signal. The adder 133 includes the first tracking error signal latch circuit 13 and the first tracking error signal latch circuit 13 latched by the first tracking error signal latch circuit 131.
The second tracking error signal latched in 2 is added, and the added value is output to the third tracking error signal latch circuit 135 as a third tracking error signal.

The subtracter 134 uses the first tracking error signal latched by the first tracking error signal latch circuit 131 to convert the first tracking error signal latch circuit 13 into the second tracking error signal latch circuit 13.
Subtract the second tracking error signal latched in 2,
The subtracted value is output to the fourth tracking error signal latch circuit 136 as the fourth tracking error signal. The third tracking error signal latch circuit 135 is the adder 1
The third tracking error signal output from 33 is latched and output to the terminal b of the selector 125. The fourth tracking error signal latch circuit 136 includes a subtractor 134
The fourth tracking error signal output from is latched and output to the terminal c of the selector 125. The first tracking error signal latched by the first tracking error signal latch circuit 131 is output to the terminal a of the selector 125.

The Schmitt device 137 has the first tracking error signal latch circuit 131 latched by the first tracking error signal latch circuit 131.
The tracking error signal is waveform-shaped at timings a and c, the second tracking error signal latched by the second tracking error signal latch circuit 132 is waveformd at timing b, and the waveform is input to the selector discriminating unit 138. The Schmitt device 137 binarizes the input tracking error signal at a certain reference level and shapes the waveform into "1" or "0". The selector discriminating unit 138 discriminates the waveform shaping signal from the Schmitt device 137 by the selector discriminating logic of the table shown in FIG. 3, and when the second tracking error signal is “0”, the selector 125 is connected to the terminal. By switching to a, the first tracking error signal is output as an original tracking error signal to a velocity phase control system of a capstan motor (not shown),
When the second tracking error signal is “1” and when the first tracking error signal is “0”, the selector 125
Is switched to the terminal c, and the fourth tracking error signal is output to the speed phase control system of the same capstan motor as the original tracking error signal. When the second tracking error signal is "1", If the tracking error signal of 1 is "1", the selector 125 is switched to the terminal b, and the third tracking error signal is output as the original tracking error signal to the speed phase control system of the same capstan motor.

FIG. 4 shows the first with respect to the tracking shift amount.
The change in the level of the tracking error signal and the change in the level of the second tracking error signal are shown. This figure corresponds to the figure in which FIGS. 13 and 14 of the conventional example are shown at the same time. Here, the Schmitt output when the Schmitt level (threshold value) of the Schmitt device 137 shown in FIG. 1 is set to “0” is shown in FIGS. 4B and 4C. FIG. 4B shows a
Alternatively, FIG. 4C shows an output obtained by simulating the first tracking error signal at the timing c, and FIG. 4C shows an output obtained by simulating the second tracking error signal at the timing b, and this output is input to the selector discriminating unit 138. .

The selector discriminator 138 makes a discrimination according to the discrimination logic shown in FIG. 3, and the selector 125 selects the tracking error signal. In the section d shown in FIG. 4C, the first tracking error signal as shown in FIG. 4D is selected and the same tracking control as the conventional one is performed, but in the section e, the first tracking error signal and the second tracking error signal The third tracking error signal obtained by adding the tracking error signals of is selected, and this error signal always exhibits a positive maximum value. Next, in the section f, the fourth tracking error signal, that is, the error signal obtained by subtracting the second tracking error signal from the first tracking error signal, is selected,
The subtraction result always shows the maximum negative value.

FIG. 4E shows the change in the tracking error signal obtained from the selector 125. As shown in the figure, the tracking error value has a trapezoidal shape with respect to the tracking deviation amount.
Even in the vicinity of 6 tracks, since the tracking error value is maximum or minimum, the operation immediately pulls the tracking to the right or left, and the unstable position where the pulling direction is not clear disappears. Further, here, the ratio of addition in the adder 133 and the ratio of subtraction in the subtractor 134 are set to 1: 1, but the ratio is not limited to this, and for example, the second tracking error signal may be used to further speed up the pull-in. It is also possible to increase the ratio at the time of the addition / subtraction of.

According to the present embodiment, when the tracking deviation amount is within ± 1 track, the tracking control is performed using the first tracking error signal which is a normal value indicating the tracking deviation of the head. When the tracking deviation amount is larger than ± 1 track, tracking control is performed using the second or third tracking error signal whose absolute value is large, so that even in the back lock position where tracking is deviated by 2 tracks. , Regular lock position tracking can be pulled in quickly without accumulating in the back lock position. Moreover, there is no need to reverse the reverse lock state to the normal lock state as in the past, so eliminate the various problems that occur when the reverse lock state is reversed to the positive lock state. You can

In this example, one head pulls in tracks every four tracks as shown in FIG. 4, so that the four head tracks used for recording and the heads for reproduction can be easily matched. Therefore, it is possible to eliminate the variation in the reproduction level due to the difference between the recording head and the reproduction head, and to always obtain a stable high-quality reproduction signal.

FIG. 5 is a block diagram showing the configuration of the second embodiment of the present invention. In this example, the third and fourth tracking error signals are not created by adding and subtracting the first and second tracking error signals, and the third and fourth tracking error signals are respectively generated by the third tracking error signal output circuit. 139, the fourth tracking error signal output circuit 140 outputs the preset fixed value to the selector 125. The reason is that the third and fourth tracking error signals used in the first embodiment always show the maximum value or the minimum value of the tracking error signal when it is selected by the selector 125. This is because there is no problem even if the maximum value is set in advance for the third tracking error signal and the minimum value is set for the fourth tracking error signal so that both signals are fixed values.

Therefore, also in this example, when the tracking deviation amount is within ± 1 track, the tracking control is performed using the first tracking error signal which is a normal value indicating the tracking deviation of the head. When the deviation amount is larger than ± 1 track, tracking control is performed using the third or fourth tracking error signal that has a large absolute value and is a fixed value. In the case of a large size, the pulling-in of the tracking to the regular position can be made very fast, and the normal lock state can be always quickly achieved without the back lock state.

Moreover, since the third or fourth tracking error signal of this example is a preset fixed value, it is possible to set the most suitable value for speeding up the pulling of the tracking to the normal position, and Since the third or fourth tracking error signal can be set to a constant value that is not affected by noise, smooth tracking control can be performed. Further, if the maximum value and the minimum value are set from the second tracking error signal level when the tracking is pulled in, the values are set in consideration of the variation in the output difference of the head, and the maximum value and the minimum value are set. Since it is automatically corrected according to the output difference of the head, smoother tracking control can be performed.

In the above embodiment, the third tracking error signal is set to the maximum value and the fourth tracking error signal is set to the minimum value. However, the phase pull-in characteristic of the capstan motor, that is, the deceleration direction is set. The fourth tracking error signal can also be set to the maximum value in consideration of the characteristic that the pull-in of tracking is slower than the pull-in in the acceleration direction. In this case, the tracking control value for the tracking deviation amount is as shown in FIG. 6, and when the tracking deviation amount deviates more than −1, the maximum value is immediately given as the fourth tracking error signal. , The tracking can be converted into the pull-in in the acceleration direction and the tracking can be quickly pulled in to the regular position, and the same effect as that of the above-described embodiment can be obtained.

FIG. 7 is a block diagram showing the configuration of the third embodiment of the present invention. This example shows an example in which the present invention is applied to a two-head system using a double azimuth head. In case of 2 heads, A1 head and B1 head with different azimuths are placed on a rotating cylinder (not shown)
It is installed facing each other. In this case, the head is 2
Since they are individual, the A1 head and the B1 head are alternately switched by the head switching device (which also serves as the reproduction switching device) 2 and are input to the bandpass filter 5 and the main signal processing circuit 13. ing.

At the time of recording, the A1 head and the B1 head are switched to form one track at a time. Eventually, the tracks recorded on the magnetic tape are the same as those in the 4-head system shown in FIG. The method of tracking control during reproduction is almost the same as that of the above-described four-head system, and the configuration of the tracking control device is exactly the same. The only difference is that each timing signal generated from the timing pulse generation circuit 130 and the timing of A / D conversion in the A / D converter 121 of the microcomputer 12 are different, and the timing relationship of this side is the timing chart of FIG. It is shown in. That is, the A / D converter 121 is the comparator 1
1 output from the frequency f1 as shown in FIG.
The digitization of the difference between the pilot signal of No. 1 and the pilot signal of frequency f2 is performed at the scanning timings a and c of the A1 head as shown in FIG. 8L, and at the scanning timing b of the B1 head. To do. Other operations are exactly the same as the four-head system, and the same effect can be obtained.

FIG. 9 is a block diagram showing the configuration of the fourth embodiment of the present invention. This example also adopts the two-head system, and the third tracking signal is generated as a fixed value from the third tracking signal output circuit 139, and the fourth tracking signal is generated.
The tracking signal of 4 is generated as a fixed value from the fourth tracking signal output circuit 140, but unlike the configuration of the third embodiment, other configurations are the same as those of the third embodiment. The operation is similar to that of the second embodiment, and has the same effect as that of the second embodiment.

[0050]

As described above, according to the tracking control apparatus and the magnetic recording / reproducing apparatus of the present invention, the tracking is always pulled into the regular lock state without reversing the back lock state to the regular lock state. You can

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of a magnetic recording / reproducing device equipped with a tracking control device of the present invention.

FIG. 2 is a timing chart explaining the operation of the device shown in FIG.

FIG. 3 is a diagram showing a table example of a discrimination logic of a selector discriminating unit shown in FIG.

FIG. 4 is a characteristic diagram showing changes in the first and second tracking error signals and changes in the tracking error signal output from the selector shown in FIG. 1, with respect to the tracking deviation amount.

FIG. 5 is a block diagram showing a configuration of a second exemplary embodiment of the present invention.

6 is a characteristic diagram showing an example of a tracking error signal output from the selector shown in FIG.

FIG. 7 is a block diagram showing a configuration of a third exemplary embodiment of the present invention.

FIG. 8 is a timing chart explaining the operation of the device shown in FIG.

FIG. 9 is a block diagram showing a configuration of a fourth exemplary embodiment of the present invention.

FIG. 10 is a diagram showing a head configuration example of a conventional magnetic recording / reproducing apparatus.

11 is a diagram showing an example of a track pattern formed by scanning the head shown in FIG.

FIG. 12 is a block diagram showing an example of a magnetic recording / reproducing device equipped with a conventional tracking control device.

13 is a characteristic diagram showing a change in a tracking error signal with respect to a tracking deviation amount of the A1 head shown in FIG.

14 is a characteristic diagram showing a change in a tracking error signal with respect to a tracking deviation amount of the B1 head shown in FIG.

15 is a characteristic diagram showing changes in the tracking error signal in the back lock state and the positive lock state after the reverse state in the device shown in FIG.

16 is a timing chart for explaining the operation when the tracking is at the positive lock position in the device shown in FIG.

FIG. 17 is a timing chart for explaining an operation when the tracking is at the back lock position in the device shown in FIG.

[Explanation of Codes] 1.1 to 1.4 ... Reproducing amplifier 2, 3 ... Head switching unit 4 ... Reproducing signal switching unit 5, 7, 8 ... Band pass filter (BPF) 6 ... Amplifier 9, 10 ... Wave detector 11 Comparator 12 Microcomputer 13 Main signal processing unit 121 A / D converters 122 and 134 Subtractor 123 Polarity inverter 124 Polarity switch 125 Selector 130 Timing pulse generation circuits 131 and 132 135, 136 ... First, second, third, fourth and fourth tracking error signal latch circuits 133 ... Adder 137 ... Schmidt device 138 ... Selector discriminating unit

Claims (8)

[Claims] 1. A magnetic tape on which a plurality of pilot signals having different frequencies are cyclically recorded in a unit of two tracks with a unit track having no pilot signal interposed therebetween, and the pilot signals are recorded on the magnetic tape. First and second scanning of the pilot signal simultaneously on two tracks each
Reproducing means for reproducing with the rotating magnetic head, first signal generating means for obtaining a first tracking error signal from a pilot signal included in a signal reproduced by the first rotating magnetic head for scanning a track, and Second signal generating means for obtaining a second tracking error signal from a pilot signal included in a signal reproduced by a second rotary magnetic head which scans an adjacent track scanned by the first rotary magnetic head; Adding means for adding the first tracking error signal created by the signal creating means and the second tracking error signal created by the second signal creating means; and the adding means created by the first signal creating means. Subtracting means for subtracting the second tracking error signal created by the second signal creating means from the first tracking error signal, The third tracking error signal obtained from the adding means, or the fourth tracking error signal obtained from the output of the subtracting means, or the first track produced by the first signal producing means. Selecting means for selecting any one of the king error signals as an original tracking error signal to be used for controlling the running phase of the magnetic tape; and the first tracking created by the first signal creating means. Determination means for determining which tracking error signal should be selected by the selection means based on the level of the error signal and the level of the second tracking error signal created by the second signal creation means. A tracking control device comprising: 2. A magnetic tape in which a plurality of pilot signals having different frequencies are cyclically recorded on a track-by-track basis with unit tracks in which no pilot signal is present sandwiched therebetween, and recorded on the magnetic tape. First and second scanning of two pilot signals simultaneously
Reproducing means for reproducing with the rotating magnetic head, first signal generating means for obtaining a first tracking error signal from a pilot signal included in a signal reproduced by the first rotating magnetic head for scanning a track, and Second signal generating means for obtaining a second tracking error signal from a pilot signal included in a signal reproduced by a second rotary magnetic head which scans an adjacent track scanned by the first rotary magnetic head; Third tracking error signal output means for outputting a third tracking error signal having a predetermined value, fourth tracking error signal output means for outputting a fourth tracking error signal having a preset value, and Either the third tracking error signal output from the third tracking error signal output means or the fourth tracking error signal. One of the fourth tracking error signal output from the signal output means or the first tracking error signal created by the first signal creating means is selected to select the signal of the magnetic tape. Selecting means for making the original tracking error signal used for traveling phase control; the level of the first tracking error signal created by the first signal creating means and the first tracking error signal created by the second signal creating means. 2. A tracking control device comprising: a determination unit that determines which tracking error signal is selected by the selection unit on the basis of the level of the tracking error signal of 2. 3. A magnetic tape on which a plurality of pilot signals having different frequencies are cyclically recorded on a track-by-track basis with a unit track in which no pilot signal is present interposed therebetween, and recorded on the magnetic tape. Reproducing means for reproducing the pilot signal by the first and second rotary magnetic heads for scanning one track respectively, and the first tracking by the pilot signal contained in the signal reproduced by the first rotary magnetic head for scanning the track. A second tracking error from a pilot signal included in a signal reproduced by a first signal generating means for obtaining an error signal and a second rotary magnetic head scanning the adjacent track scanned by the first rotary magnetic head. Second signal producing means for obtaining a signal, and a first tracking error signal produced by the first signal producing means. No. and the second tracking error signal generated by the second signal generating means, and the second signal from the first tracking error signal generated by the first signal generating means. A subtracting means for subtracting the second tracking error signal created by the creating means, and a third tracking error signal obtained from the adding means, or a fourth tracking error signal obtained from the output of the subtracting means, Alternatively, selecting means for selecting one of the first tracking error signals created by the first signal creating means to be an original tracking error signal used for running phase control of the magnetic tape. , The level of the first tracking error signal created by the first signal creating means and the level of the first tracking error signal created by the second signal creating means Tracking control apparatus being characterized in that; and a determination means for performing determination whether to select one of a tracking error signal by the selection means based on the level of the second tracking error signal. 4. A magnetic tape in which a plurality of pilot signals having different frequencies are cyclically recorded on a track-by-track basis with a unit track having no pilot signal interposed therebetween, and the magnetic tape is recorded on the magnetic tape. Reproducing means for reproducing the pilot signal by the first and second rotary magnetic heads for scanning one track respectively, and first tracking from the pilot signal included in the signal reproduced by the first rotary magnetic head for scanning the track. A second tracking error from a pilot signal included in a signal reproduced by a first signal generating means for obtaining an error signal and a second rotary magnetic head scanning the adjacent track scanned by the first rotary magnetic head. Second signal generating means for obtaining a signal, and third for outputting a third tracking error signal having a preset value Tracking error signal output means, fourth tracking error signal output means for outputting a fourth tracking error signal having a preset value, and third tracking error signal output means for outputting the third tracking error signal output means. Either the tracking error signal, the fourth tracking error signal output from the fourth tracking error signal output means, or the first tracking error signal generated by the first signal generating means. Selecting means for selecting one of the signals as an original tracking error signal to be used for controlling the running phase of the magnetic tape; the level of the first tracking error signal created by the first signal creating means; The selecting means based on the level of the second tracking error signal created by the second signal creating means Tracking control apparatus being characterized in that; and a determination unit to perform a more or decision to select one of a tracking error signal. 5. A third tracking error signal output from the third tracking error signal output means and a fourth tracking error signal output from the fourth tracking error signal output means.
The tracking control device according to claim 2 or 4, wherein the polarities of the tracking error signals of are opposite to each other. 6. A third tracking error signal output from the third tracking error signal output means and a fourth tracking error signal output from the fourth tracking error signal output means.
The tracking control device according to claim 2 or 4, wherein the tracking error signals have the same polarity. 7. A determination means for determining the selection of the selection means based on the level of the second tracking error signal and the level of the first tracking error signal compares the first tracking error signal with a predetermined value. First to distinguish between two values
And a second binary discriminating means for discriminating into a binary value by comparing the second tracking error signal with a predetermined value, and the second binary discriminating means is a first value. Is the first when
The tracking error signal is selected and the second binary discriminating means indicates the second value, the value indicated by the first binary discriminating means is the first value or the second value. 5. The tracking control device according to claim 1, wherein one of the third tracking error signal and the fourth tracking error signal is selected depending on whether or not 8. A magnetic recording / reproducing apparatus for recording / reproducing information on / from a magnetic tape by a plurality of magnetic heads on a rotating cylinder, wherein the reproducing magnetic head and the reproducing magnetic head are provided by using the tracking control device according to any one of claims 1 to 7. A magnetic recording / reproducing apparatus characterized by performing tracking control between tracks on a magnetic tape.