JP3338816B2 - Magnetic tape unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic tape device and, more particularly, to a magnetic tape device which monitors data bit intervals at the time of writing with respect to speed fluctuation of a magnetic tape to prevent writing of data having abnormal bit intervals. It relates to a tape device.

[0002]

2. Description of the Related Art Conventionally, a magnetic tape device of this type is provided with a write head 101 and a read head 102 as means for monitoring whether or not writing is normally performed, as shown in FIG. In the traveling direction, the write head 101 precedes the read head 102.
Is arranged, and the data written by the write head 101 is read by the read head 102 immediately after the writing, and is read by a read while write (Read While Wr.).
item) method is generally used.

[0003] Since data is written by the write head 101 at the same time interval (constant frequency), if the running speed of the magnetic tape 103 becomes faster than the normal speed, the data interval is written longer, and conversely, the magnetic tape 103 is written. Tape 1
03 If the running speed is lower than the normal speed, the data interval is written short, but in the read-while-write method, when the magnetic tape 103 passes through the write head 101 and the read head 102, Therefore, even if the running speed of the magnetic tape 103 fluctuates, the running distance of the magnetic tape 103 with respect to the data writing time does not look abnormal, and therefore, the write data interval is different from the normal running speed of the magnetic tape 103. There is a drawback that it cannot be determined that the data is abnormal as compared with the data interval at the time.

[0004]

As described above,
In the above-described conventional read / write / write type magnetic tape device, the speed at which the magnetic tape passes through the write head and the read head is the same. However, there is a problem that it is impossible to determine that the data interval is abnormal as compared with a data interval at a normal magnetic tape running speed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic tape device in which data bit intervals of data are prevented from being written abnormally by monitoring bit intervals of data at the time of writing with respect to speed fluctuations of magnetic tape running. is there.

[0006]

According to the present invention, there is provided a magnetic tape drive comprising: a write head for writing data on a magnetic tape;
A read head for reading data written on a magnetic tape, a read data generating circuit for generating data read by the read head, and a first PLL for generating a read pulse based on the read data generated by the read data generating circuit (Phase Locked Loop) circuit, a servo head that reads a servo pattern of a servo track written in advance on a magnetic tape, a servo data generation circuit that generates a servo pattern read by the servo head, and a servo data generation circuit A second PLL circuit that generates a servo pulse based on the obtained servo data, a data interval monitoring circuit to which outputs of the first PLL circuit and the second PLL circuit are input, and an output from the data interval monitoring circuit to be input. A drive control unit,
The data interval monitoring circuit includes a counter to which the outputs of the first PLL circuit and the second PLL circuit are input, a first logic circuit to which the output of the counter is input, and an output from the first logic circuit connected to the set input. A flip-flop circuit to which an output from the first PLL circuit is input as a clock signal;
A second logic circuit to which an inverted output from the flip-flop circuit and an output of the second PLL circuit are input;

The counter counts a read pulse generated by the first PLL circuit and is reset by a servo pulse generated by the second PLL circuit.

The first logic circuit outputs 1 when the counter has a certain value, and sets the flip-flop circuit.

The flip-flop circuit is characterized in that it is a D-type flip-flop circuit.

[0010] The flip-flop circuit is characterized in that the D input is grounded.

[0011] The second logic circuit is characterized in that when both the input from the flip-flop circuit and the input from the second PLL circuit are 1, it outputs 1 to the drive control unit as a data interval abnormality.

The first logic circuit and the second logic circuit are both AND circuits.

The data interval monitoring circuit monitors whether the data interval written on the magnetic tape is normal or abnormal, and reports an abnormal data interval to the drive control unit if the data interval is abnormal. .

[0014] The drive control unit is characterized in that it controls running, writing and reading of the magnetic tape.

The servo head is characterized in that it has means for reading a servo pattern of a servo track previously written on the magnetic tape and performing positioning control in the tape width direction of the magnetic tape.

The servo pattern is characterized in that the patterns at the minimum interval are written at equal intervals.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a magnetic tape device according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic block diagram showing a magnetic tape device 30 of the present invention, and FIG. 2 is a diagram showing servo tracks 21 on a magnetic tape 20 and servo patterns 22 of the servo tracks 21.

Referring to FIGS. 1 and 2, a magnetic tape device 30 includes a write head (not shown) for writing data on the magnetic tape 20 and a read head 1 for reading data written on the magnetic tape 20. A read data generating circuit 3 for generating data read by the read head 1, and a first PL for generating a data pulse c based on the read data b generated by the read data generating circuit 3.
An L circuit 4, a servo head 2 for reading a servo pattern 22 of a servo track 21 previously written on a magnetic tape 20, a servo data generation circuit 5 for generating a servo pattern 22 read by the servo head 2, Servo data e generated by the generation circuit 5
A second PLL circuit 6 for generating a servo pulse f based on
A data interval monitoring circuit 12 to which outputs of the first PLL circuit 4 and the second PLL circuit 6 are input, and a data interval monitoring circuit 1
The data interval monitoring circuit 12 receives the output of the first PLL circuit 4 and the second PLL circuit 6 and receives the output of the first PLL circuit 4.
And a counter 7 which counts a data pulse c generated by the counter and is reset by a servo pulse f generated by the second PLL circuit 6, and a first AND to which an output of the counter 7 is input.
A circuit 8, an output from the first AND circuit 8 is connected to a set input, an output from the first PLL circuit 4 is input as a clock signal, and a D input is grounded; A second AN to which the inverted output from the flop circuit 9 and the output of the second PLL circuit 6 are input
And a D circuit 10.

The drive control unit 11 controls running, writing, and reading of the magnetic tape 20, and the servo head 2 reads a servo pattern 22 of a servo track 21 written on the magnetic tape 20 in advance.
The magnetic tape 20 is configured to perform positioning control in the width direction of the tape 20.

Further, the patterns at the minimum intervals of the servo patterns 22 are written and formed at equal intervals.

Next, the operation of the magnetic tape device 30 configured as described above will be described with reference to the drawings.

FIG. 3 shows a data reproduction signal, read data,
FIG. 4 shows servo patterns, servo data, and servo pulses.

Referring to FIGS. 3 and 4, the data written on the magnetic tape 20 is read out by the read head 1 as a data reproduction signal a, generated by the read data generation circuit 3 as read data b, and The first PLL circuit 4 generates the data pulse c following the read data b having the shortest interval.

On the other hand, the servo pattern 22 is read out by the servo head 2, generated as servo data e by the servo data generation circuit 5, and further generated by the PLL circuit 6 as a servo pulse f following the servo data e having the shortest interval. Generated.

Here, when the magnetic tape 20 runs at a specified speed, the data pulse c is generated every time the servo pulse f is generated.
Is assumed to generate 10 pulses, and the data interval monitoring circuit 1
The operation 2 will be described below with reference to the drawings.

FIG. 5 shows a data pulse a, a servo pulse f, and a first A when the magnetic tape 20 runs at a specified speed.
FIG. 9 is a diagram showing an ND circuit output g, a D-type flip-flop circuit inverted output h, and a second AND circuit output k.

Referring to FIGS. 1 and 5, when the magnetic tape 20 runs at a specified speed, the counter 7 is reset by the servo pulse f after counting 10 data pulses c. The counter 7 repeats this operation.

The first AND circuit 8 outputs the value of the counter 7 of 10
, 1 is output and the D-type flip-flop circuit 9 is set.

When the servo pulse f is input to the second AND circuit 10, the value of the counter 7 is 10, so that the D-type flip-flop circuit 9 is in the set state, and the D-type flip-flop circuit inverted output h is Since 0 is output to the second AND circuit 10, the output k of the second AND circuit does not output 1 to the drive control unit 11.

Next, the operation of the data interval monitoring circuit 12 when the magnetic tape 20 is faster than the prescribed running speed will be described.
This will be described with reference to the drawings.

FIG. 6 shows the data pulse a, the servo pulse f, and the data pulse a when the magnetic tape 20 runs faster than a prescribed speed.
FIG. 9 is a diagram showing a first AND circuit output g, a D-type flip-flop circuit inverted output h, and a second AND circuit output k.

Referring to FIGS. 1 and 6, when the magnetic tape 20 is faster than a prescribed running speed, the servo pulse f
Is shorter, and the counter 7 outputs the data pulse c
Is reset by the servo pulse f before counting by 10 pulses, the D-type flip-flop circuit 9 is reset.
Is not set, the inverted output h of the D-type flip-flop circuit becomes 1, and when the servo pulse f is input to the second AND circuit 10, the output k of the second AND circuit becomes
1 is output to the drive control unit 11, and the data interval abnormality is reported to the drive control unit 11.

Next, the operation of the data interval monitoring circuit 12 when the magnetic tape 20 is slower than the prescribed running speed will be described.
This will be described with reference to the drawings.

FIG. 7 shows a data pulse a, a servo pulse f, and a data pulse a when the magnetic tape 20 runs at a speed lower than a specified speed.
FIG. 9 is a diagram showing a first AND circuit output g, a D-type flip-flop circuit inverted output h, and a second AND circuit output k.

Referring to FIGS. 1 and 7, when the magnetic tape 20 is slower than a prescribed running speed, the servo pulse f
The D-type flip-flop circuit 9, which is set only when the value of the counter 7 is 10, is
When the servo pulse f is input to the second AND circuit 10, the value of the counter 7 is not 10, so that the counter 7 is not in the set state, but the D-type flip-flop circuit inverted output h
Becomes 1.

Therefore, the second AND circuit 10 outputs 1 to the drive control unit 11 and reports an abnormal data interval to the drive control unit 11.

[0038]

As described above, the magnetic tape device of the present invention is generated by reading the servo pulse generated from the servo pattern previously written on the magnetic tape and the actually written data. Since the time interval with the data pulse is compared, it is possible to monitor the data bit interval at the time of writing with respect to the speed fluctuation of the magnetic tape running, and to prevent the data writing when the bit interval is abnormal. There is an effect that data reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing a magnetic tape device of the present invention.

FIG. 2 is a diagram showing servo tracks on a magnetic tape and servo patterns on the servo tracks.

FIG. 3 is a diagram showing a data reproduction signal, read data, and data pulses.

FIG. 4 is a diagram showing servo patterns, servo data, and servo pulses.

FIG. 5 is a diagram showing a data pulse, a servo pulse, a first AND circuit output, a D-type flip-flop circuit inverted output, and a second AND circuit output when the magnetic tape runs at a specified speed.

FIG. 6 shows a data pulse, a servo pulse, a first AND circuit output when the magnetic tape runs faster than a prescribed speed,
FIG. 9 is a diagram showing a D-type flip-flop circuit inverted output and a second AND circuit output.

FIG. 7 shows a data pulse, a servo pulse, an output of a first AND circuit, when the magnetic tape runs slower than a prescribed speed;
FIG. 9 is a diagram showing a D-type flip-flop circuit inverted output and a second AND circuit output.

FIG. 8 is a schematic configuration diagram showing a read-while-write system of a conventional magnetic tape device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 read head 2 servo head 3 read data generation circuit 4 first PLL circuit 5 servo data generation circuit 6 second PLL circuit 7 counter 8 first AND circuit 9 D-type flip-flop circuit 10 second AND circuit 11 drive control unit 12 Data interval monitoring circuit 20 Magnetic tape 21 Servo track 22 Servo pattern 30 Magnetic tape device 101 Write head 102 Read head 103 Magnetic tape a Data reproduction signal b Read data c Data pulse e Servo data f Servo pulse g First AND circuit output h D Type flip-flop circuit inverted output k Output of second AND circuit

Claims (11)

(57) [Claims] 1. A write head for writing data on a magnetic tape, a read head for reading data written on the magnetic tape, a read data generation circuit for generating data read by the read head, and the read data A first PLL circuit for generating a read pulse based on the read data generated by the generation circuit, a servo head for reading a servo pattern of a servo track previously written on a magnetic tape, and the servo read by the servo head A servo data generation circuit for generating a pattern, and a second PL for generating a servo pulse based on the servo data generated by the servo data generation circuit
An L circuit; a data interval monitoring circuit to which outputs of the first PLL circuit and the second PLL circuit are input; and a drive control unit to which an output from the data interval monitoring circuit is input. An interval monitoring circuit, a counter to which outputs of the first PLL circuit and the second PLL circuit are input, a first logic circuit to which an output of the counter is input,
A flip-flop circuit in which an output from the first logic circuit is connected to a set input and an output from the first PLL circuit is input as a clock signal, an inverted output from the flip-flop circuit, and the second PLL circuit And a second logic circuit to which an output of the magnetic tape is input. 2. The magnetic tape device according to claim 1, wherein the counter counts a read pulse generated by the first PLL circuit and is reset by a servo pulse generated by the second PLL circuit. 3. The magnetic tape device according to claim 1, wherein the first logic circuit outputs 1 when the counter has a certain value, and sets the flip-flop circuit. 4. The flip-flop circuit according to claim 1, wherein said flip-flop circuit is a D-type flip-flop circuit.
Or the magnetic tape device according to 3. 5. The magnetic tape device according to claim 1, wherein the flip-flop circuit has a D input grounded. 6. The second logic circuit outputs 1 to the drive control unit as a data interval abnormality when an input from the flip-flop circuit and an input from the second PLL circuit are both 1. 6. The method according to claim 1, wherein
The magnetic tape device according to claim 1. 7. The magnetic tape device according to claim 1, wherein the first logic circuit and the second logic circuit are both AND circuits. 8. The data interval monitoring circuit monitors whether a data interval written on the magnetic tape is normal or abnormal, and reports an abnormal data interval to the drive control unit if abnormal. The magnetic tape device according to claim 1, wherein: 9. The magnetic tape device according to claim 1, wherein the drive control unit controls running, writing, and reading of the magnetic tape. 10. The servo head further comprises means for reading out the servo pattern of the servo track previously written on the magnetic tape and performing positioning control in the tape width direction of the magnetic tape. The magnetic tape device according to claim 1, wherein 11. The magnetic tape device according to claim 1, wherein the servo patterns are written at a minimum interval pattern at equal intervals.