JP3430732B2 - Magnetic recording / reproducing apparatus and magnetic recording / reproducing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention records / records digital video signals, digital audio signals, etc. on a magnetic tape.
Regarding the reproducing apparatus, more specifically, ATF (Auto
TECHNICAL FIELD The present invention relates to a technique for suppressing a change in loop gain of servo.

[0002]

2. Description of the Related Art A magnetic recording / reproducing method has been proposed in which a plurality of rotating magnetic heads record / reproduce an ATF pilot signal together with information signals such as digital video signals and digital audio signals on a magnetic tape.

FIG. 10 shows the relationship between the track pattern and the ATF pilot signal in such a magnetic recording / reproducing method, and FIG. 11 shows the frequency spectrum of the ATF pilot signal in the track of FIG.

As shown in FIGS. 10 and 11, on the tracks F1 and F2, pilot signals of frequencies f1 and f2 are recorded. On the other hand, in the track F0, notches of the components of the frequencies f1 and f2 are formed. The pilot signals and notches of these frequencies f1 and f2 are added by converting a digital signal to be recorded or the like into 24-25 conversion in a channel encoder. Then, during reproduction, tracking control is performed so that the head reproducing the track F0 has equal crosstalk components of the pilot signals f1 and f2 of the adjacent tracks F1 and F2.

FIG. 12 shows the format of each track shown in FIG. In FIG. 12, the left end of the track is the head entrance (rush) side, and the right side is the head exit (separation) side. An ITI area, an audio data recording area, a video data recording area, and a subcode data recording area are provided in order from the left end of the track. Data is not recorded in the overwrite margin provided at the right end of the track and the IBG (inter block gap) provided between the data areas.

As described above, the pilot signal component and the notch are added by converting the recording data by 24-25, but they are processed so that the reproduction level of these components becomes high in the ITI area.

[0007]

According to the present invention, in the magnetic recording / reproducing method having the basic structure as described above, the angle θ formed by the longitudinal direction of the magnetic tape and the scanning direction of the track is 8
It is larger than the magnetic recording / reproducing apparatus for analog recording such as millivideo, that is, the track is standing. Therefore, highly accurate tracking control technology is required.

The present invention has been made in view of the above circumstances, and provides a new and useful apparatus and method for realizing highly accurate tracking control in the magnetic recording / reproducing method having the above-mentioned basic structure. The purpose is to provide.

[0009]

In order to solve the above problems, a magnetic recording / reproducing apparatus according to the present invention comprises a first track on which data is recorded / reproduced by a magnetic head of a first channel, and a second track. The first pilot detected at a high level during reproduction in a predetermined area of the first track of the magnetic tape in which the second track on which data is recorded / reproduced by the magnetic head of the channel is alternately arranged. The signal and the first pilot signal have different frequencies
Is a magnetic recording / reproducing apparatus having a format in which the pilot signals of are alternately recorded in track units, and when reproducing the data from the second track in which the data is recorded according to the format, The first pilot signal and the second pilot signal recorded in a predetermined area of the first track formed on both sides of the track are detected, and the level of the first pilot signal and the second pilot signal are detected. Error signal generating means for generating an error signal based on the level difference; and a first pilot signal and a first pilot signal recorded in a predetermined area of the first track when reproducing data from the first track. Control means for controlling the gain of the error signal based on the level difference between the two pilot signals, and the gain is controlled by the control means. Based on the error signal and a tracking control means for controlling the tracking of the first channel of the magnetic head and a second channel of the magnetic head. In order to solve the above-mentioned problems, a magnetic recording / reproducing method according to the present invention uses a first track on which data is recorded / reproduced by a magnetic head of a first channel and a data recording by a magnetic head of a second channel. The first pilot signal detected at a high level during reproduction and the first pilot in a predetermined area of the first track of the magnetic tape in which the second tracks for recording / reproducing are alternately arranged. A signal is a magnetic recording / reproducing method having a format in which second pilot signals having different frequencies are alternately recorded in track units, and the data is reproduced from the second track in which data is recorded according to the format. The first pilot recorded in a predetermined area of the first track formed on both sides of the second track. No. and detecting a second pilot signal, a level of the first pilot signal second
When an error signal is generated based on the difference in the level of the pilot signal of, and the data is reproduced from the first track,
The gain of the error signal is controlled based on the level difference between the first pilot signal and the second pilot signal recorded in the predetermined area of the first track, and the gain is controlled based on the error signal whose gain is controlled. The tracking control of the magnetic head of the first channel and the magnetic head of the second channel is controlled.

Here, the first track is recorded such that the level of the pilot signal reproduced from a predetermined area is relatively high, and the level difference of the pilot signal reproduced from this area is recorded. It is preferable to use it to control the gain.

Further, when the first track is reproduced, the levels of the pilot signals of the first and second frequencies reproduced from the first track are compared to determine the polarity of the error signal, and the polarity is determined. It is preferable to shorten the pull-in time by performing tracking control based on the error signal.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a main part of a magnetic recording / reproducing apparatus to which the present invention is applied. Since the present invention relates to tracking during reproduction, a block diagram during reproduction is shown.

This magnetic recording / reproducing apparatus has a magnetic head H for reproducing the digital data recorded on the magnetic tape 1.
0, H1, RF amplifiers 2 and 3 for amplifying the reproduced signals of the magnetic heads H0 and H1, and a switch SW1 for alternately switching the outputs of the RF amplifiers 2 and 3 to form a time series.

The magnetic heads H0 and H1 are provided on the outer circumference of a rotary drum (not shown) at positions opposite to each other by 180 degrees and have different azimuth angles. Then, the magnetic head H0 is controlled to scan the track F0 in FIG. 10, and the magnetic head H1 is controlled to alternately scan the tracks F1 and F2. The switch SW1 is switched according to the rotation of the rotary drum by a head switching signal generated by the microcomputer 5 described later.

The magnetic recording / reproducing apparatus shown in FIG. 1 further includes an ATF circuit 4 for generating an ATF error from an RF signal passed through a switch SW1, a microcomputer (hereinafter referred to as a microcomputer) 5 for controlling the entire apparatus, and a microcomputer 5. Generates a motor drive signal in accordance with the speed command signal generated by the DA converter circuit 6, the capstan motor 7, and the microcomputer 5, which converts the gain control signal generated by the analog signal to the gain control amplifier 14 in the ATF circuit 4 and applies the analog signal. In addition, a capstan driver 8 for applying to the capstan motor 7 is provided.

The microcomputer 5, based on the capstan FG detecting the rotation frequency of the capstan motor, the drum PG detecting the rotation phase of the rotating drum, the drum FG detecting the rotation frequency of the rotating drum, and the ATF error, Generate a speed command signal. Further, the head switching signal described above is generated from the drum PG and the drum FG. further,
A gain control signal is generated from the level of the ATF error.
Details of the processing of the microcomputer 5 described above will be described later.

The ATF circuit 4 includes a bandpass filter 9 for extracting a pilot signal component of frequency f1 from an input RF signal, a bandpass filter 10 for extracting a pilot signal component of frequency f2, and a bandpass filter 9.
Circuit for rectifying the output of the bandpass filter 10, a rectifier circuit for rectifying the output of the bandpass filter 10, a subtractor 13 for taking a difference between the output levels of the rectifier circuit 11 and the rectifier circuit 12, and an output level of the subtractor 13. It is composed of a gain control amplifier 14 for adjustment and a low-pass filter 15 for taking out a low frequency component of the output of the gain control amplifier 14 and generating an ATF error.

Next, the basic concept of the tracking control in this embodiment will be described with reference to the relationship between the track pattern and the head in FIG. In the present embodiment, the head H0 reproduces the track F0, and tracking control is performed so that the crosstalk components of the pilot signals f1 and f2 of the adjacent tracks F1 and F2 are equal. At this time, when the head H0 is in the position shown by A in the figure, F2 is on the left side and F1 is on the right side, but when it is at the position shown by B in the figure, F1 is on the left side and F2 is on the right side. The polarity of the ATF error is alternately inverted. On the other hand, the ATF error when the head H1 scans is such that the output of the rectifying circuit 11 corresponding to the level of the pilot signal of the frequency f1 is maximized when the track F1 is scanned as shown in FIG. When the track F2 is scanned as shown in D of the figure, the output of the rectifying circuit 12 corresponding to the level of the pilot signal of the frequency f2 is maximized, so that the ATF error is alternately increased to plus or minus. Shake.

In the present embodiment, the difference between the level of the ATF error that causes the maximum positive shift and the level of the ATF error that causes the maximum negative shift during the scanning of the head H1 is used.
Generate a gain control signal.

Further, in the present embodiment, the level of the ATF error that causes the maximum positive swing and the level of the ATF error that causes the maximum negative shift during the scanning of the head H1 are compared, and the ATF error during the scanning of the head H0 is detected. Determine the polarity. In other words, it is determined which of the F1 track and the F2 track is being scanned by the head H1, and as a result, F1, to the left and right of the track F0 scanned by the head H0 next.
F2 is for determining which track exists. As a result, it is possible to shorten the pull-in time until tracking.

Next, the general operation of the apparatus shown in FIG. 1 will be described with reference to the timing chart of FIG. The signals alternately reproduced from the magnetic tape 1 by the heads H0 and H1 are amplified by the RF amplifiers 2 and 3, and the switch SW1
Is time-series. 3A shows a head switching signal for switching the switch SW1, and FIG. 3B shows a time-sequential RF signal. In FIG. 3B, C
H0 indicates the reproduction signal of the head H0, and CH1 indicates the head H.
1 shows a reproduction signal of 1.

RF time-series by switch SW1
The signal is input to the ATF circuit 4, and after undergoing gain control, an ATF error is detected. FIG. 3C shows an ATF error.

In FIG. 3 (c), E, F, and G correspond to the ITI portion of the maximum shaken ATF error obtained from the head H1. Further, H and J in FIG. 3C are ATF error voltages used for tracking control. In the present embodiment, the gain control signal is generated by using the difference between the levels of E and F or F and G, and the polarities of H and J are compared by comparing the levels of E and F or F and G. Determine.

The ATF error shown in FIG. 3C is sent to the microcomputer 5. The microcomputer 5 samples the ATF errors such as E, F, G, H, and J described above in the timing shown in FIG.

FIG. 4 is a block diagram showing the internal functions of the microcomputer 5. The microcomputer 5 uses the ATF error capturing unit 2
1, a gain control signal calculation unit 22, and a polarity determination unit 23
, CH0 side ATF error calculator 24, and multiplier 25
And a speed command signal calculator 26.

The ATF error fetching section 21 stores the input ATF error at the timing shown in FIG. 3 (d). This timing is generated by the drum PG and the drum FG.
It is realized by counting an internal clock (not shown) with reference to. The ATF error fetching section 21 further generates a head switching signal. The timing of the head switching signal is also generated in the same way as the timing of capturing the ATF error.

FIG. 5 shows an example of the configuration of the ATF error fetching section 21. The drum rotation phase detection processing unit 31, for example, after detecting the rising of the drum PG, outputs a reference pulse indicating the timing of the first rising of the drum FG. The timing generation circuit 32 counts an internal clock from the timing of the reference pulse to generate a head switching signal and an AD conversion start signal as shown in FIGS. 3A and 3D. AD conversion circuit 33
When the AD conversion start signal is received, the sample the input ATF error and capture it in the AD data storage register 34. Then, a capture end signal is output each time one sample is captured. In FIG. 5, the timing generation circuit 32, the AD conversion circuit 33, and the AD data storage register 34 are incorporated as a circuit in the microcomputer 5,
A capture end signal is connected to the CPU (not shown), and A
It is configured so that an interrupt process at the end of D conversion can be activated.

As shown in FIG. 4, the gain control signal calculation unit receives the AD data of E, F, and G of FIG. 3C from the ATF error acquisition unit 21, and uses the level difference to obtain the gain control signal. To generate.

The processing of the gain control signal calculator 22 is shown in FIG. This process is started by receiving the capture end signal from the ATF error capture unit 21. First,
The AD data stored in the AD data storage register 34 of the ATF error capturing unit 21 is received. And
The subtracter 42 calculates the difference S between the received AD data and the sample stored in the reception buffer 41 at the previous startup.
Calculate in. Then, after calculating the difference S, the sample of the AD data received this time is stored in the buffer 41.

As a result, the level difference between E and F or F and G in FIG. 3C can be obtained. This level difference is F
Since the signs are inverted between -E and GF, the sign of S is judged in the sign judgment circuit 43, and if the sign is negative, the switches SW1 and SW2 are switched to the side of the coefficient unit 44 whose coefficient is -1. , Convert to a positive value.

In this way, when the level difference of the ITI portion of the ATF error with the maximum fluctuation on the CH1 side is detected,
This level difference is compared with the target voltage in the subtractor 45,
Further, an integrating circuit 46, coefficient units 47 and 48, and an adder 49
Gives an integral characteristic and a proportional characteristic, and the adder 50
A gain control signal is generated by adding a bias at.

The gain control signal generated as described above is sent to the DA converter 6, where it is converted into an analog level signal and used for controlling the gain control amplifier 14. As a result, the gain of the gain control amplifier 14 is controlled according to the target voltage applied to the subtractor 45.

The process of generating the speed command signal will be described below. As shown in FIG. 4, the polarity determination unit 23 receives the AD data of E, F, and G of FIG. 3D from the ATF error acquisition unit 21 and outputs the result K of which the polarity is determined.

FIG. 7 shows an example of the configuration of the polarity discriminating section 23.
FIG. 7 shows a process for discriminating the polarity by using the ATF error level (E, F, G, etc.) in the ITI portion of FIG.
This process is started by receiving the capture end signal from the ATF error capture unit 21. And AT
AD data storage register 34 of F error acquisition unit 21
Receives AD data stored in CH1
If the AD data is a sample of the ATF error of the ITI portion on the side, the previously read A of the ITI portion on the CH1 side
The size of the TF error is compared with the sampled AD data, and the result K is calculated (52). At this time, since the AD data obtained by sampling the ATF error of the ITI portion on the CH1 side that was previously read is stored in the buffer 51, it is read from here. Then, after calculating the result K, the AD data received and used for comparison is newly stored in the buffer 51.

The result K is, for example, 1 if the current level ≧ the previous level, and −1 if the current level <the previous level. With this value, for example, E in FIG.
It is possible to determine whether it is F or G. Therefore, the polarity of the next ATF error on the CH0 side can be determined.

As shown in FIG. 4, the CH0 side ATF error calculating section 24 receives the AD data of the CH0 side ATF error from the ATF error fetching section 21, and calculates the ATF error L for each track.

FIG. 8 shows the processing of the CH0 side ATF error calculating section. According to the present invention, a plurality of samples are recorded over the entire track in order to stably apply servo even when the track is relatively curved as in the case of compatible reproduction (reproduction of a track recorded by another device). To A
Generate a TF error. In the present embodiment, FIG.
As shown in, an ATF error sample of 6 points per track is used.

The process shown in FIG. 8 is started by receiving the end signal of taking in each sample. First, when the AD data received from the AD storage register 34 is the first point, the ATF error value is written to the RAM as it is, and the process ends (61). Then, in the case of the 2nd to 6th points, the ATF error values are sequentially added, and the result L obtained by adding up to the 6th point is output (62).

As shown in FIG. 4, the output K of the polarity discriminating unit 23 and the output L of the CH0 side ATF error calculating unit 24 are multiplied by the multiplier 25, and the AT including the polarity information is included.
An F error M results and is sent to the speed command signal calculation unit 26. The speed command signal calculation unit 26 calculates a speed command signal using the output M and the capstan FG, and gives it to the capstan driver 8 in FIG.

FIG. 9 shows the structure of the speed command signal calculating section 26. The speed command signal calculator 25 subtracts the target voltage from the output M of the adder 25 to calculate a phase error.
And a capstan phase servo operation unit 72 that performs predetermined processing (integration, gain adjustment, etc.) on this phase error,
A cycle calculator 73 for calculating the cycle of the capstan FG,
A subtracter 74 that calculates a speed error by subtracting the target cycle from the cycle of the capstan FG, and a capstan speed servo calculation unit 75 that performs a predetermined process on the speed error.
And an adder 76 for adding the output of the capstan phase servo operation unit 72 and the output of the capstan speed servo operation unit 75 to generate a speed command signal.

In the above embodiment, the I on the CH1 side is
Although the gain control signal was created and the polarity of the ATF error on the CH0 side was determined by using the ATF error in the TI part, the ATF error at one or more points was sampled from the entire track on the CH1 side, and it was used. The gain control signal may be created and the polarity may be determined.

Further, in the above-described embodiment, the notches having the frequencies f1 and f2 are formed in the track on the CH0 side, but the notches may not be formed. Furthermore, the frequency f1
Pilot signals of frequencies other than and f2 may be recorded.

In the above embodiment, the microcomputer 5
Has created a gain control signal and a speed command signal, but part or all of these processes may be configured by logic.

[0044]

As described above in detail, according to the present invention, when reproducing is performed in a predetermined area of the first track of the magnetic tape in which the first track and the second track are alternately arranged. Since the first pilot signal and the second pilot signal detected at a high level have a format in which they are alternately recorded in track units, when reproducing the data recorded on the magnetic tape according to the above format, the ATF servo The loop gain of can be controlled to a predetermined level, and highly accurate and stable tracking control can be realized. Therefore, even if the reproduction RF level of the pilot signal changes due to the difference in the type of magnetic tape or the variation in characteristics, it is possible to suppress the change in the loop gain of the ATF servo and realize stable tracking control.

Further, since the unlock point can be instantly switched to the lock point by determining the polarity of the error signal, the pull-in time until tracking can be shortened. In addition, the track is discontinuous due to failure in joint shooting (CH0 side or CH
Even if the lock point changes to the unlock point because the number of tracks on the 1st side is two), the tracking can be switched to the lock point in the same manner, so that the tracking is not disturbed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a main part of a magnetic recording / reproducing apparatus to which the present invention is applied.

FIG. 2 is a diagram showing a relationship between a track pattern and a head.

FIG. 3 is a timing chart showing a schematic operation of the device shown in FIG.

FIG. 4 is a block diagram showing internal functions of the microcomputer shown in FIG.

5 is a diagram showing a configuration of an ATF error fetching unit in FIG.

FIG. 6 is a diagram showing a process of a gain control signal calculation unit in FIG.

FIG. 7 is a diagram showing a process of discriminating the polarity by using the level of the ATF error in the ITI portion.

FIG. 8 is a diagram showing a process of a CH0-side ATF error calculation unit in FIG.

9 is a diagram showing a configuration of a speed command signal calculation unit in FIG.

FIG. 10 is a diagram showing a relationship between a track pattern and an ATF pilot signal in a conventional magnetic recording / reproducing method.

11 is a diagram showing a frequency spectrum of an ATF pilot signal in the track of FIG.

12 is a diagram showing a format of each track in FIG.

[Explanation of symbols]

1 ... Magnetic tape, 4 ... ATF circuit, 5 ... Microcomputer, H
0, H1 ... Magnetic head, 21 ... ATF error capturing section, 22 ... Gain control signal calculating section, 23 ... Polarity determining section,
24 ... CH0 side ATF error calculator, 25 ... Multiplier,
26 ... Speed command signal calculator

Claims (4)

(57) [Claims] 1. A first track on which data is recorded / reproduced by a magnetic head of a first channel and a second track on which data is recorded / reproduced by a magnetic head of a second channel are arranged alternately. A first pilot signal detected at a high level during reproduction and a second pilot signal whose frequency is different from that of the first pilot signal in a predetermined area of the first track of the magnetic tape A magnetic recording / reproducing apparatus having a format of recording alternately, which is formed on both sides of the second track when the data is reproduced from the second track in which the data is recorded according to the format. The first pilot signal and the second pilot signal recorded in a predetermined area of the first track are detected and the first pilot signal is detected. Error signal generating means for generating an error signal based on the difference between the signal level and the level of the second pilot signal, and recording the data in a predetermined area of the first track when reproducing data from the first track. Control means for controlling the gain of the error signal based on the level difference between the first pilot signal and the second pilot signal, and the first channel based on the error signal whose gain is controlled by the control means. And a tracking control means for controlling tracking of the magnetic head of the second channel. 2. The tracking control means comprises the first
When reproducing data from the track, the levels of the first pilot signal and the second pilot signal recorded in the predetermined area of the first track are compared, and the polarity of the error signal is calculated from the comparison result. 2. The magnetic recording / reproducing apparatus according to claim 1, wherein the magnetic recording / reproducing apparatus is characterized in that the tracking control is performed based on the polarity of the determined error signal. 3. A first track on which data is recorded / reproduced by a magnetic head of a first channel and a second track on which data is recorded / reproduced by a magnetic head of a second channel are arranged alternately. A first pilot signal detected at a high level during reproduction and a second pilot signal whose frequency is different from that of the first pilot signal in a predetermined area of the first track of the magnetic tape A magnetic recording / reproducing method having a format to be recorded alternately, which is formed on both sides of the second track when the data is reproduced from the second track in which the data is recorded according to the format. The first pilot signal and the second pilot signal recorded in a predetermined area of the first track are detected and the first pilot signal is detected. An error signal is generated based on the difference between the signal level and the level of the second pilot signal, and when data is reproduced from the first track, the first signal recorded in a predetermined area of the first track is recorded. The gain of the error signal is controlled based on the level difference between the pilot signal and the second pilot signal, and the magnetic head of the first channel and the magnetic head of the second channel are controlled based on the error signal whose gain is controlled. A magnetic recording / reproducing method characterized by controlling tracking. 4. When reproducing data from the first track, the levels of a first pilot signal and a second pilot signal recorded in a predetermined area of the first track are compared, 4. The polarity of the error signal is determined from the comparison result, and tracking control is performed based on the determined polarity of the error signal.
The magnetic recording and reproducing method described.