Tracking controller for a tape-like recording medium

Details Tracking controller for a tape-like recording medium Tracking controller for a tape-like recording medium

2000-01-20

2001-07-24

Sniezek, Andrew L. (Department: 2651)

Dynamic magnetic information storage or retrieval

Automatic control of a recorder mechanism

Controlling the record

C360S018000, C360S077150, C360S077130

Reexamination Certificate

active

06266204

ABSTRACT:

TECHNICAL FIELD
This invention relates to a tracking control apparatus for a tape-shaped recording medium. Specifically, this invention relates to an apparatus adapted for controlling relative velocity between traveling velocity of the tape-shaped recording medium and rotational velocity of the rotary drum to provide (apply) tracking servo (control).
BACKGROUND ART
There have been developed, e.g., Digital Audio Tape Players (hereinafter simply referred to as DAT) adapted for recording and/or reproducing digital audio data with respect to magnetic tape and Digital Data Storages in which such DAT is used to record or reproduce data of the computer. In these devices, magnetic tape is traveled in the state where the magnetic tape is wound at a wrap angle of, e.g., 90 degrees on the rotary drum, and the rotary drum is rotated to carry out recording/reproduction in accordance with the helical scan system by using the magnetic head on the rotary drum. Thus, high density recording is permitted.
In accordance with this helical scan system, inclined tracks TK
A
, TK
B
are formed on the magnetic tape as shown in FIG.
1
. These inclined tracks TK
A
, TK
B
are tracks formed by, e.g., recording in which no guard band is provided (so-called azimuth full recording) by using a pair of recording heads HR
A
, HR
B
in which azimuth angles are different from each other mounted on the rotary drum. In more practical sense, respective gaps GP of the recording heads HR
A
, HR
B
are adapted so that azimuth angles é
A
, é
B
are provided in directions opposite to each other, and magnetization (magnetic polarization) directions of the inclined tracks TK
A
, TK
B
are different from each other as indicated by slanting lines. In this azimuth full recording, the track width TP is narrower than the width of the recording heads HR
A
, HR
B
.
Meanwhile, at the time of reproduction, the magnetic head is required to precisely trace tracks TK (inclined tracks TK
A
, TK
B
) on the magnetic tape. As this tracking control system, e.g., in the digital data storage, a tracking servo control so called timing ATF (Automatic Track Following) system is used.
In accordance with this timing ATF system, the time (or time period which will be referred to as tracking detection time) required from the reference phase position of the rotary drum until the magnetic head detects (reproduces) a predetermined signal (hereinafter referred to as a timing detection signal) from corresponding track is measured to compare that measured value and reference value to allow error therebetween to be servo error information. Then, the rotational velocity (speed) of the capstan motor for traveling the magnetic tape is controlled on the basis of this servo error information to adjust the tape traveling velocity. Namely, the tape traveling velocity is adjusted to adjust the relative velocity between the drum rotational velocity and the tape traveling velocity so that a satisfactory tracking state can be obtained.
In more practical sense, as shown in
FIG. 3
, phase position of the rotary drum when scanning position of the magnetic head is caused to be the position of line (timing) designated as TR
A
in
FIG. 3
with respect to a certain track is caused to be the reference phase position. At the rotary drum or the drum motor, pulse generator (PG) is disposed. At the time point when the rotary drum is located at the reference phase position during rotation, a pulse signal is generated from the PG. Accordingly, it is possible to detect the timing TR
A
at which the rotary drum has been located at the reference phase position. Thereafter, when the magnetic head comes into contact with the magnetic tape to scan the inclined track TR
A
, a timing detection signal is detected as reproduction data at a predetermined position P
TTP
on the track. This timing detection signal serves so that pulse can be obtained at the predetermined position P
TTP
such as synchronizing signal or address, etc. included in reproduction data.
In this case, three different kinds of scanning loci in the tracking phase state of the magnetic head with respect to the inclined track TK
A
are designated as {circle around (
1
)}, {circle around (
2
)}, {circle around (
3
)} in FIG.
3
. The times from the timing when the magnetic head is located at the reference phase position (position of the line TR
A
) of the rotary drum up to the timing when the magnetic head reaches the position P
TTP
, i.e., tracking detection times are different from each other as respectively designated as t
1
, t
2
, t
3
in the scanning states of {circle around (
1
)}, {circle around (
2
)}, {circle around (
3
)}.
As the reference value of the tracking detection time, time t
1
obtained when the magnetic head is placed in the satisfactory tracking state with respect to the track TK, i.e., in the state where it traces the center of the inclined track TK
A
as in the case of {circle around (
1
)} is set in advance. Accordingly, in the case where scanning as in the case of {circle around (
1
)} is carried out at the time of tracking servo control so that time t
1
is measured as the tracking detection time, the measured value becomes in correspondence with the reference value. Namely, in this case, there is no error between the measured value and the reference value, and there results satisfactory tracking state. On the other hand, in the case where scanning is carried out in the tracking phase state as in the case of {circle around (
2
)} or {circle around (
3
)}, the measured value of the tracking detection time becomes equal to t
2
or t
3
, giving rise to error with respect to the reference value. In this case, there results the state where tracking deviates by that error. By reflecting this with respect to the tape traveling velocity, the servo control then results in just the tracking state can being carried out.
In providing (applying) tracking servo (control) by such timing ATF system, it is necessary to determine in advance the reference value. This reference value is the time (time period) from the timing of the reference phase position of the rotary drum in the just tracking state to the timing at which the timing detection signal is detected. Since the timing detection signal is generated, e.g., on the basis of detection of synchronizing signal, etc. at a predetermined position on the track, that position P
TTP
should be fixed at each track of various tapes. However, from a practical point of view, it cannot be avoided that positional shift may take place resulting from mechanical error, etc. at various recording equipments and reproducing equipments. For this reason, in the digital data storage, in the case where certain file data is reproduced, it is necessary to measure, prior to read-out of that data, the reference value at that tape (its file data track).
In this measurement of the reference value, there is conducted such a processing to carry out scanning in various tracking phase states with respect to the tracks to calculate, from tracking detection times measured at respective scanning operations, e.g., an average value of these detection times to allow such an average value to be the reference value.
Its operation image is shown in FIG.
4
. As shown in
FIG. 4
, when scanning is carried out in plural tracking phase states TJ
1
~TJ
5
different from each other with respect to, e.g., the inclined track TK
A
to calculate an average value of respective tracking detection times measured in those scanning operations, tracking detection time in the tracking phase state in the vicinity of the tracking phase state TJ
3
is obtained. This tracking detection time is permitted to be tracking detection time substantially in the just tracking state. Therefore, it is sufficient to employ this tracking detection time as the reference value.
Meanwhile, in the digital data storage etc., reproduction must be carried out with good compatibility with respect to tape cassettes recorded by various recording devices. When this applies to tracking, satisfactory tracking servo controls by the timing AT

Affiliated with

Also associated with

Rating

Tracking controller for a tape-like recording medium does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Tracking controller for a tape-like recording medium, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tracking controller for a tape-like recording medium will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2538394