JP3430735B2 - Magnetic reproducing apparatus and magnetic reproducing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for reproducing a digital video signal, a digital audio signal, etc. recorded on a magnetic tape, and more specifically, an ATF (A
The present invention relates to a technique for determining the polarity of an automatic track finding (error) error and shortening the pull-in time of the ATF servo.

[0002]

2. Description of the Related Art A magnetic recording / reproducing method has been proposed in which an ATF pilot signal (hereinafter simply referred to as a pilot signal) is recorded / reproduced together with information signals such as digital video signals and digital audio signals on a magnetic tape by a plurality of rotating magnetic heads. ing.

FIG. 7 shows the relationship between the track pattern, the pilot signal and the magnetic head in such a magnetic recording / reproducing method, and FIG. 8 shows the frequency spectrum of the pilot signal in the track of FIG.

As shown in FIGS. 7 and 8, the track F1
And F2, pilot signals of frequencies f1 and f2 are recorded, respectively. On the other hand, in the track F0,
Notches of the components of the frequencies f1 and f2 are formed. These frequency f1 and f2 pilot signals and notches are
The digital information signal to be recorded is given by being converted by the channel encoder 24-25. And
During reproduction, the pilot signals f1 and f of the tracks F1 and F2 adjacent to the magnetic head H0 that has scanned the track F0 are adjacent to each other.
Tracking control is performed so that the crosstalk components of 2 have the same level.

FIG. 9 shows the format of each track shown in FIG. In FIG. 9, 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.
The contents of these data recording areas can be rewritten by post-recording. 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]

A device shown in FIG. 10 is considered as a device for detecting an ATF error during reproduction in the above-described magnetic recording / reproducing method of the format. In this figure, the magnetic heads H0 and H1 are provided at positions opposite to each other by 180 degrees on the outer circumference of a rotary drum (not shown), and have different azimuth angles. Then, the magnetic head H0 scans the track F0 in FIG.
The magnetic head H1 is controlled to alternately scan the tracks F1 and F2.

Magnetic tape 1 by magnetic heads H0 and H1
The signals alternately reproduced from are amplified by the RF amplifiers 2 and 3, and are time-sequentialized by the switch SW1. Figure 11
11A shows a head switching signal for switching the switch SW1, and FIG. 11B shows a time series RF signal. Further, in FIG. 11B, CH0 represents the reproduced signal of the head H0, and CH1 represents the reproduced signal of the head H1.

RF time-series by switch SW1
The signal is input to the ATF circuit 4. In the ATF circuit 4, the pilot signal component of frequency f1 is extracted by the bandpass filter 11, and the pilot signal component of frequency f2 is extracted by the bandpass filter 12. Then, these components are rectified by the rectifier circuits 13 and 14, the difference between the rectified outputs is detected by the subtractor circuit 15, and further passed through the low-pass filter 16 to generate an ATF error.

The ATF error generated in this way is shown in FIG. 11 (c). The ATF error on the CH0 side is the difference between the crosstalk components of the pilot signals f1 and f2 of the adjacent tracks F1 and F2. This has a polarity that alternates depending on which of the F1 and F2 tracks exists on the left and right of the head H0. Invert. Further, the polarity of the ATF error on the CH1 side is alternately inverted between when the track F1 is being scanned and when the track F2 is being scanned, and the ATF error swings positively or negatively to the maximum.

However, since the ATF circuit 4 has a circuit such as a bandpass filter, a detection circuit, and a lowpass filter that causes a time delay, the CH1 side swings to the maximum as shown in A of FIG. 11 (c). ATF error is CH0
It will remain on the side. For this reason, if the ATF error is sampled at the timing shown in FIG. 11D and the tracking control voltage is created using the average value of the ATF error, it is affected by the residual amount on the CH1 side, which is accurate. The tracking control voltage cannot be created.

An object of the present invention is to provide a magnetic reproducing apparatus and a magnetic reproducing method which solve the above problems.

[0013]

In order to solve the above-mentioned problems, the present invention provides recording / reproducing with a first track and a second channel magnetic head for recording / reproducing with a first channel magnetic head. The second tracks are alternately arranged, and the pilot signal of the first frequency and the pilot signal of the second frequency are alternately recorded in track units on the first track. A magnetic reproducing apparatus for reproducing a magnetic tape having a format in which neither the pilot signal of the first frequency nor the second frequency is recorded, wherein the signal reproduced from the first track and the second signal are reproduced. Switching means for alternately switching a signal reproduced from a track at predetermined time intervals, and a signal reproduced from the first track when reproducing the first track Means for blocking a predetermined section of the second track, an error signal obtained from a signal reproduced from the second track, and a first signal obtained from a signal reproduced from a first track on both sides of the second track. It is characterized by further comprising a calculating means for calculating the speed command signal from the polarity of the error obtained by comparing the pilot signal components of the first and second frequencies.

Here, the cut-off means detects the signal reproduced from the first track before obtaining the pilot signal components of the first and second frequencies from the signal reproduced from the first track. Shut off.

Further, according to the present invention, the first tracks recorded / reproduced by the magnetic head of the first channel and the second tracks recorded / reproduced by the magnetic head of the second channel are alternately arranged. , A pilot signal of a first frequency and a pilot signal of a second frequency are alternately recorded on the first track in track units, and the pilot signal of the first or second frequency is recorded on the second track. A magnetic reproducing method for reproducing a magnetic tape having a format in which none of the signals is recorded, wherein the signal reproduced from the first track and the signal reproduced from the second track are at predetermined time intervals. Alternately, the predetermined section of the signal reproduced from the first track is interrupted when the first track is reproduced, and the second track is reproduced.
Comparing an error signal obtained from the signal reproduced from the first track and a pilot signal component of the first and second frequencies obtained from the signals reproduced from the first track on both sides of the second track. The speed command signal is calculated from the polarity of the error obtained by.

The magnetic reproducing apparatus and the magnetic reproducing method according to the present invention mean an apparatus and a method for reproducing at least a magnetic tape. That is, it includes an apparatus and method for recording / reproducing on / from a magnetic tape.

[0017]

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 reproducing apparatus to which the present invention is applied. Here, the same parts as those in FIG. 10 are denoted by the same numbers.

This magnetic reproducing apparatus has magnetic heads H0, H for reproducing digital signals recorded on the magnetic tape 1.
1 and RF for amplifying the reproduction signals of the magnetic heads H0 and H1
The amplifiers 2 and 3 and the switch SW1 that alternately switches the outputs of the RF amplifiers 2 and 3 to form a time series are provided.

The magnetic heads H0 and H1 are provided at positions opposite to each other by 180 degrees on the outer circumference of a rotary drum (not shown) and have different azimuth angles. The magnetic head H0 is controlled to scan the track F0 in FIG. 7, 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 reproducing apparatus of FIG. 1 further includes a switch S.
An AT that generates an ATF error from the RF signal that has passed through W1
An F circuit 4, a microcomputer (hereinafter referred to as a microcomputer) 5 that controls the entire apparatus, and a capstan motor 6
And a capstan driver 7 for generating a motor drive signal according to a speed command signal generated by the microcomputer 5 and applying it to the capstan motor 6.

The microcomputer 5 uses the capstan FG that detects the rotation frequency of the capstan motor, the drum PG that detects the rotation phase of the rotating drum, the drum FG that detects 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,
The switch SW2 in the ATF circuit 4 is turned off for a predetermined period to generate an RF cut signal for cutting the input RF signal. Details of the processing of the microcomputer 5 described above will be described later.

The ATF circuit 4 includes a switch SW2 for turning on / off an input RF signal, a bandpass filter 11 for extracting a pilot signal component of frequency f1 from the RF signal passing through the switch SW2, and a pilot signal component of frequency f2. A bandpass filter 12 for extracting the signal, a rectifying circuit 13 for rectifying the output of the bandpass filter 11,
Rectifier circuit 14 for rectifying the output of the bandpass filter 12.
, A subtraction circuit 15 for taking a difference between the output levels of the rectification circuit 13 and the rectification circuit 14, and a low-pass filter 16 for extracting a low-frequency component of the output of the subtraction circuit 15 and generating an ATF error.
It consists of and.

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. 2A shows a head switching signal for switching the switch SW1, and FIG. 2B shows a time-sequential RF signal. In FIG. 2B, 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-serialized by the switch SW1
The signal is input to the ATF circuit 4, and after the RF signal in a part of the section is cut by the switch SW2, the bandpass filters 11 and 12, the rectifier circuit 13, and
An ATF error is detected by 14, the subtraction circuit 15, and the low-pass filter 16. An RF cut signal is shown in FIG. 2C, and an ATF error is shown in FIG.

As shown by B in FIG. 2D, RF
In the section where the input is cut off by the cut signal, the ATF error becomes the center value, and the same error voltage as in the center-tracked state can be created. Therefore,
Since CH0 side does not show the influence of CH1 plus or minus maximum ATF error, AT on CH0 side
Even if the F error is sampled at the timing shown in FIG. 2E, an accurate tracking control voltage can be created. The ATF error voltage of the ITI portion on the CH1 side shown in C of FIG. 2D is used for AGC control of the ATF error voltage on the CH0 side, polarity determination, and the like.

The ATF error shown in FIG. 2D is sent to the microcomputer 5. The microcomputer 5 samples the above-mentioned ATF error on the CH0 side and the CH1 side by the timing shown in FIG.

FIG. 3 is a block diagram showing the internal functions of the microcomputer 5. The microcomputer 5 uses the ATF error capturing unit 2
1, a CH0 side ATF error calculation unit 22, a polarity determination unit 23, a multiplier 24, and a speed command signal calculation unit 25.

The ATF error fetching section 21 stores the input ATF error at the timing shown in FIG. 2 (e). 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 and an RF cut signal.
The timing of these signals is also generated in the same way as the timing of capturing the ATF error.

FIG. 4 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 the internal clock from the timing of the reference pulse to obtain the head switching signal, the RF cut signal, and the AD conversion as shown in FIGS. 2A, 2C, and 2E. Generate a start signal.

Upon receiving the AD conversion start signal, the AD conversion circuit 33 samples the input ATF error and
The data is stored in the data storage register 34. Then, a capture end signal is output each time one sample is captured. In FIG. 4, the timing generation circuit 32 and the AD conversion circuit 3
3 and the AD data storage register 34 are incorporated as a circuit in the microcomputer 5, and the capture end signal is CP.
It is connected to U (not shown) and is configured to be able to activate interrupt processing at the end of AD conversion.

As shown in FIG. 3, the CH0 side ATF error calculating section 22 receives the AD data of the CH0 side ATF error from the ATF error fetching section 21, and calculates the ATF error D for each track.

FIG. 5 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 this embodiment mode, FIG.
As shown in, an ATF error sample of 6 points per track is used.

The process of FIG. 5 is started by receiving the signal of the end of taking in each sample. First, when the AD data received from the AD data storage register 34 is the first point, the ATF error value is written to the RAM as it is, and the process ends (41). Then, in the case of the 2nd to 6th points, the ATF error values are sequentially added, and the result D obtained by adding up to the 6th point is output (42).

As shown in FIG. 4, the polarity discriminator 23 is AT
From the F error capturing unit 21 to A in C of FIG.
The D data is received, and the result E obtained by discriminating the polarity of the ATF error from the level is output. In this polarity determination, for example, the levels of two consecutive AD data in C are compared, and if the current value is smaller than the previous value, it is determined to be negative this time. On the contrary, if the current value is larger than the previous value, it is determined to be positive this time. Then, +1 or -1 is output according to the determination result.

As shown in FIG. 3, the output D of the CH0 side ATF error calculating section 22 and the output E of the polarity discriminating section 23 are multiplied by a multiplier 24, and the AT including the polarity information is included.
An F error F occurs and is sent to the speed command signal calculation unit 25. The speed command signal calculator 25 calculates a speed command signal using the input F and the capstan FG, and supplies it to the capstan driver 7 in FIG.

FIG. 6 shows the structure of the speed command signal calculating section 25. The speed command signal calculation unit 25 subtracts the target voltage from the output F of the CH0 side ATF error calculation unit 22 to calculate a phase error, and a predetermined process (integration, gain adjustment, etc.) for this phase error. ), A cycle calculator 53 that calculates the cycle of the capstan FG, a subtracter 54 that subtracts the target cycle from the cycle of the capstan FG to calculate a speed error, and A capstan speed servo calculation unit 55 that performs a predetermined process on an error, and an adder that adds the output of the capstan phase servo calculation unit 52 and the output of the capstan speed servo calculation unit 55 to generate a speed command signal. And 56.

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

Further, in the above-described embodiment, the microcomputer 5 creates the speed command signal, the RF cut signal, etc., but a part or all of these processes may be configured by logic.

[0039]

As described above in detail, according to the present invention, recording / reproducing is performed by the first track and the second channel magnetic head which are recorded / reproduced by the magnetic head of the first channel. The second tracks are alternately arranged, and the pilot signal of the first frequency and the pilot signal of the second frequency are alternately recorded on the first track in track units, and the first track is recorded on the second track. When reproducing a magnetic tape having a format in which the pilot signal of the second frequency and the pilot signal of the second frequency are not recorded, an error signal corresponding to the level difference between the pilot signal components of the first and second frequencies is generated. Since it is not affected by the reproduction signal of the first track, an accurate tracking control voltage can be created.

[Brief description of drawings]

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

FIG. 2 is a timing chart showing an ATF error detecting operation in the magnetic reproducing apparatus of FIG.

FIG. 3 is a block diagram showing internal functions of the microcomputer shown in FIG.

FIG. 4 is a diagram showing a configuration of an ATF error acquisition unit in FIG.

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

FIG. 6 is a diagram showing a configuration of a speed command signal calculation unit in FIG.

FIG. 7 is a diagram showing a relationship between a track pattern, a pilot signal, and a magnetic head in a conventional magnetic recording / reproducing method.

8 is a diagram showing a frequency spectrum of a pilot signal in the track of FIG.

9 is a diagram showing a format of each track in FIG. 7. FIG.

FIG. 10 is a diagram showing a configuration of a device for detecting a conventional ATF error.

11 is a timing chart showing an ATF error detection operation in the apparatus of FIG.

[Explanation of symbols]

1 ... Magnetic tape, 4 ... ATF circuit, 5 ... Microcomputer, H
0, H1 ... Magnetic head

Claims (4)

(57) [Claims] 1. A first track recorded / reproduced by a magnetic head of a first channel and a second track recorded / reproduced by a magnetic head of a second channel are alternately arranged, and the first track is formed. Of the first frequency and the pilot signal of the second frequency are alternately recorded on the track No., and the pilot signal of the first or second frequency is recorded on the second track. A magnetic reproducing apparatus for reproducing a magnetic tape having an unrecorded format, the signal being reproduced from the first track and the second signal.
Alternating the signal reproduced from the track at predetermined time intervals
And switching means for switching, a blocking means for blocking a predetermined section of the signal reproduced from the first track during playback of the first track, d obtained from the signal reproduced from the second track
Error signal and the first tracks on both sides of the second track
The first and second frequencies obtained from the signal reproduced from
Obtained by comparing the number of pilot signal components
A magnetic reproducing apparatus comprising: a calculating unit that calculates a speed command signal based on the polarity of an error . 2. The breaking means is the first track.
From the signal reproduced from the first and second frequency pyro
From the first track before obtaining the input signal component.
2. A signal to be reproduced is cut off.
The magnetic reproducing device described. 3. A first track recorded / reproduced by a magnetic head of a first channel and a second track recorded / reproduced by a magnetic head of a second channel are alternately arranged, and the first track is formed. to track the pilot signal of the pilot signal and the second frequency of the first frequency is alternately recorded in track units, it said the second track any of the first or second frequency of the pilot signal A magnetic reproducing method for reproducing a magnetic tape having an unrecorded format, comprising a signal reproduced from the first track and the second signal.
Signal that will be reproduced from the track are alternately at predetermined time intervals
, And when the first track is played back, the first track is restarted.
The signal obtained from the signal reproduced from the second track is cut off by cutting off a predetermined section of the generated signal.
Error signal and the first tracks on both sides of the second track
The first and second frequencies obtained from the signal reproduced from
Obtained by comparing the number of pilot signal components
A magnetic reproducing method characterized by calculating a speed command signal from the polarity of an error . 4. The signal reproduced from the first track is cut off before the pilot signal components of the first and second frequencies are obtained from the signal reproduced from the first track. The magnetic reproducing method according to claim 3, which is characterized in that