Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the record
Reexamination Certificate
2000-05-09
2003-04-01
Hudspeth, David (Department: 2651)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the record
C360S074200, C360S096100
Reexamination Certificate
active
06542323
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a tape-thickness measuring method, and a tape-running control method using the tape-thickness measuring method. In particular, the present invention relates to a tape-thickness measuring method in which a belt-type recording medium is caused to run at a fixed speed, and a tape-running control method using the tape-thickness measuring method.
2. Description of the Related Art
A DDS (Digital Data Storage) has been developed as a large-capacity data backing-up device. In the DDS, backup data is recorded in a recording format of a DAT (Digital Audio Tape-recorder). In the DAT, a magnetic tape is caused to run at a fixed speed, data is recorded on the magnetic tape, and, also, data is reproduced from the magnetic tape. A belt-type recording medium such as a magnetic tape has a capacity larger than that of a disk-type recording medium. Therefore, when a large amount of data should be backed up, the DDS is useful.
FIG. 1
shows a general arrangement of one example of DDS in the related art.
In the DDS in the related art, when data is recorded or reproduced, a magnetic tape
3
contained in a DAT tape cassette
2
is drawn out from a supply reel
4
, is caused to run through supply poles
5
and a guide roller
6
, and is wound on a rotation drum
7
through a predetermined angle. Then, the magnetic tape
3
is caused to run through take-up poles
8
and a guide roller
9
, and is drawn into a take-up reel
10
of the DAT tape cassette
2
.
At this time, the magnetic tape
3
is sandwiched by a capstan shaft
11
a
rotated by a capstan motor
11
and a pinch roller
12
on the side of the take-up reel
10
, and is caused to run at a fixed speed as a result of being driven by the rotating capstan shaft
11
a.
At this time, the running speed of the magnetic tape
2
is determined by the rotation speed of the capstan shaft
11
a
, that is, the rotation speed of the capstan motor
11
. Therefore, in order to make the running speed of the magnetic tape
2
be fixed, the rotation speed of the capstan motor
11
is maintained to be fixed.
For this purpose, an FG (Frequency Generator)
13
is attached to the capstan motor
11
, the rotation of the capstan motor
11
is detected through the FG
13
, and the rotation speed of the capstan motor
11
is fixed by servo control. Thereby, the running speed of the magnetic tape
2
is maintained to be fixed.
However, in the DDS system
1
in the related art shown in
FIG. 1
, the running speed of the magnetic tape is maintained to be fixed as a result of servo control being performed on the capstan motor
11
. In such a system, it is necessary that the magnetic tape
3
be sandwiched by the capstan shaft
11
a
and the pinch roller
12
. Therefore, because the tape thickness is reduced as high-density data storage is achieved, the tape may be damaged.
A magnetic recording and reproducing apparatus in a capstan-less system has been proposed, in which apparatus the take-up reel is rotated by a reel motor, and, as a result of rotating the take-up reel so that the running speed of the magnetic tape is fixed, the capstan motor is omitted.
As such a magnetic recording and reproducing apparatus in the capstan-less system, a magnetic recording and reproducing apparatus is disclosed by Japanese Laid-Open Patent Application No. 9-500477, for example.
In the magnetic recording and reproducing apparatus disclosed in Japanese Laid-Open Patent Application No. 9-500477, in accordance with servo information previously written in a magnetic tape, the rotation of a take-up reel is controlled by a reel motor so that the running speed of the magnetic tape is fixed. In the magnetic recording and reproducing apparatus disclosed in Japanese Laid-Open Patent Application No. 9-500477, it is necessary to write special servo information on the magnetic tape. Therefore, it is not possible to reproduce data from a magnetic tape on which such special servo information is not recorded.
Therefore, a magnetic recording and reproducing apparatus has been proposed in which the running speed of a magnetic tape is detected by using an encoder, and the rotation speed of a take-up reel is controlled by a reel motor by using the thus-detected tape running speed.
FIG. 2
shows a block diagram of another example of a magnetic recording and reproducing apparatus in the related art. In the FIG., the same reference numerals are given to the parts the same as those shown in
FIG. 1
, and descriptions thereof will be omitted.
In the magnetic recording and reproducing apparatus
100
, an encoder
101
is provided instead of a capstan shaft. The running speed of the magnetic tape
3
is detected in accordance with the rotation of the encoder
101
. A detection signal produced by the encoder
101
is provided to a control circuit
102
.
The control circuit
102
controls the rotation speed of a reel motor
103
, which rotates a take-up reel
10
, by using the detection signal.
The take-up reel
10
is.driven by the reel motor
103
and fixes the speed at which the magnetic tape
3
is taken up by the take-up reel
10
, thus maintaining the running speed of the magnetic tape
3
to be fixed.
In a magnetic recording and reproducing apparatus in which a tape running speed is detected by an encoder or the like, and rotation of a take-up reel is controlled by a reel motor by using the detected running speed of a magnetic tape, it is necessary to provide an encoder or the like instead of a capstan motor. Thereby, miniaturization of the magnetic recording and reproducing apparatus cannot be achieved, and, also, because the encoder is expensive, cost reduction of the magnetic recording and reproducing apparatus cannot be achieved.
Further, an encoder shaft, which is rotated by the magnetic tape and rotates the encoder, is in contact with the magnetic tape, and is rotated by using a friction force. Thus, the encoder detects the running speed of the magnetic tape. Therefore, when the magnetic tape slides on the encoder shaft, an error occurs between the actual running speed of the magnetic tape and the detection signal of the encoder. Thereby, it is not possible to precisely control the running speed of the magnetic tape.
Therefore, the applicant of the present application proposed, in Japanese Patent Application No. 9-262430, a tape running method, in which tape running is controlled only by using the rotation periods of a supply reel and a take-up reel.
In the magnetic recording and reproducing apparatus in the related art in which the running speed of the magnetic tape is fixed by the capstan motor, because it is necessary to provide the capstan motor, pinch roller and so forth, miniaturization and cost reduction cannot be achieved. Further, the magnetic tape, the thickness of which is reduced, may be damaged.
In the magnetic recording and reproducing apparatus disclosed in Japanese Laid-Open Patent Application No. 9-500477, the rotation of the take-up reel is controlled by the reel motor, so that the running speed of the magnetic tape is fixed, by using the servo information previously written on the magnetic tape. Therefore, recording or reproducing cannot be performed on the magnetic tape on which the servo information has not been written.
In the magnetic recording and reproducing apparatus in which the running speed of the magnetic tape is detected through the encoder-or the like, and the rotation of the take-up reel is controlled by the reel motor by using the detected tape running speed, because it is necessary to provide the encoder or the like instead of a capstan motor, miniaturization of the apparatus cannot be achieved, and, also, because the encoder is very expensive, cost reduction of the apparatus cannot be achieved.
Further, the encoder shaft, which is rotated by the magnetic tape and rotates the encoder, is in contact with the magnetic tape, and is rotated by using a friction force. Thus, the encoder detects the running speed of the magnetic tape. Therefore, when the magnetic tape slides on the encoder
Hudspeth David
Ladas & Parry
Mitsumi Electric Co. Ltd.
Tzeng Fred F.
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