JPH043017B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a capstan control circuit for a magnetic tape device, and more particularly to a magnetic tape device position control system that takes into account pseudo interblock gaps on the magnetic tape.

[Prior Art] In a magnetic tape device, when information is written to or read from a magnetic tape, the upper part is recorded and reproduced block by block, and when the magnetic tape is stopped during information processing, the information is written between blocks.
The drive of the magnetic tape is controlled so that the read/write head is located in the IBG (interblock gap).

FIG. 1 is a block diagram showing an example of a capstan control circuit for controlling the driving of the magnetic tape as described above in a magnetic tape device.

The capstan motor section 1 includes a capstan motor 2, a tachometer 3, and a capstan 4.

Its shape is as shown in _the principle diagram of a capstan motor in _FIG . A combination circuit ₃₂ consisting of two sets of light emitting elements and light receiving elements arranged so as to generate signals having a phase difference of 90° is arranged.

In Fig. 1, 5 is a capstan drive unit, and when a control signal generated by processing the signal sent from the tachometer 3 by various circuits described below is input, this drive unit converts it from DA to DA and amplifies it by a power amplifier. Then, a drive current is output to the motor 2.

Two types of pulse signals CTPA are output from tachometer 3.
and CTPB are output, but both signals have a phase difference of 90° as described above.

These pulse signals CTPA and CTPB are the rotation information section 6
It is input to the capstan logic circuit section 7 and outputs three types of signals: a capstan speed signal CP, a capstan distance signal QTP, and a capstan rotation direction discrimination signal OD.

Here, the capstan distance signal QTP is a pulse signal used to count the running distance of the magnetic tape, and the capstan rotation direction determination signal
OD is a signal indicating the relationship between the rotation directions before stopping and after restarting, and outputs "0" if the directions are the same, and "1" if they are different.

Figure 3 is a diagram showing a capstan tacho pulse time chart to explain the generation of the above signals, and the left half of the diagram is for the case where the magnetic tape is running in the forward direction from the file reel to the machine reel. The right half shows the opposite direction.

The top row of the diagram represents the timing clock, which in this example is 1.6 μs (microseconds).

The second stage CPA and third stage CPB are respectively
Tachometer pulses shaped from CTPA and CTPB, with a 90° phase difference as shown.

The QTP in the second row from the bottom of the diagram is a distance signal pulse output as the capstan distance signal, which occurs at each rising and falling edge of the tachometer pulses CPA and CPB.
Four QTP signal pulses are generated per period.

CP shown at the bottom of the figure is a pulse signal output as the speed signal, and is generated every time the tachometer pulse CPA rises.

In the capstan logic circuit section 7, the control circuit 8 is a section that controls the main processing of this section by executing a control program based on a microprogram, and is connected to a computer main body or a higher-level device such as a magnetic tape device general control device ( an operation command CMD inputted from (not shown), a signal CP and a signal OD inputted from the rotation information section 6;
In response to the signal R from the reel control system (not shown) and the output of the IBG counter 9, etc., which will be described later,
Signals for starting, stopping, speed control, designating the rotational direction, etc. of the capstan are generated and output to the capstan drive section 5.

IBG counter 9 of capstan logic circuit section 7
is a preset command from the control circuit 8.
When a value is set in PRST via the "preset" path shown in the figure, QTP signal pulses are counted up from the set value, and when the count value reaches a predetermined limit value (128 or 256 in this example). ,Control signal
This is a circuit designed to output IBGC.

Therefore, the control circuit 8 controls the IBG counter 9
By setting an appropriate value to the control signal, when the magnetic tape has been driven the desired distance,
You can be notified by IBGC.

Figure 4 is a time chart explaining how to create an IBG. In the diagram, time progresses from left to right. The top row is the write data, and when one block of data has been written, the IBG is separated. This shows a state in which the next one block is written.

The second stage of the figure shows the write/read execution command GO. When the writing of one block of data is completed, the signal of the "GO" command falls, and when the execution of the next write operation starts, the "GO" command signal drops again. GO” command has been issued (signal has gone up).

The third row in the figure is the tape speed, which is 0 when stopped.
The fourth stage shows the tachometer pulse CTPA.

When the “GO” command falls, the gap control signal GAPC shown in the bottom row of the diagram is transmitted, and the control circuit 8 is shown in the second row from the bottom of the diagram.
For example, set the IBG counter 9 to "79".
Therefore, the IBG counter 9 continues counting the QTP signal pulses from ``79'' to ``80'', ``81'', and so on.
When the count value reaches one limit value "128", it operates to output an IBGC signal to the control circuit 8.

That is, by setting "79" in the IBG counter 9, the IBGC signal pulse is transmitted to the control circuit 8 when the 128-79=49th QTP signal pulse is counted.

The control circuit 8 uses this as an opportunity to start processing of stop control, sets "92" in the IBG counter 9, and outputs 128-92=36th QTP signal pulse.
In addition to receiving the IBGC signal, a signal is issued to slow down and stop the tape speed of the magnetic tape, and by receiving the IBGC signal, it is confirmed that the tape has traveled the required distance.

When the "GO" command is issued again for the next write, the tape starts running and, for example, "93" is added to the IBG counter 9 to establish "221".
The IBG counter 9 starts counting up by the QTP signal pulse as described above, but in this case, when counting the 35th QTP signal pulse (= 256-221), the IBG counter is controlled by the carry to 256. The signal is sent to circuit 8.

The control circuit 8 starts write control using the IBGC signal as a trigger, but as is clear from the above results, there is a gap between adjacent data blocks.
The number of QTP signal pulses counted by the IBG counter as described above, i.e. 49 + 36 + 35 = 120 QTP
An IBG with a distance corresponding to the signal pulse will be provided.

[Problem to be solved by the invention]

The magnetic tape is shown in the top row of Figure 5.
Data block on magnetic tape denoted as MT
During DBF, pseudo-IBGs such as those shown as PIBGs may be created.

This kind of pseudo-IBG can occur due to a fault in the magnetic tape device that causes a crease in the magnetic tape during magnetic tape running control, or a defect in the material of the magnetic tape recording medium that causes a missing part of the recording medium. This is caused by the generation of defective parts of the reading.

In such a pseudo IBG, the level of the read signal decreases, so it may be mistaken as an IBG with no signal, and if it is misidentified, the data block with the pseudo IBG is read and processed as if it ended at that position. This causes problems in the reproduction of recorded data in this data block and subsequent data blocks.

The object of the present invention is to provide a magnetic tape device position control system that can identify such magnetic tape failures and stop the magnetic tape at a normal IBG position.

[Means to solve the problem]

The object of the present invention is to provide a magnetic tape device, which comprises a pulse generating means, an IBG counter, a travel control means, a check counter, and a control means, and the magnetic tape device writes data blocks on a magnetic tape. When recording a magnetic tape, a gap formed by a reference IBG distance is provided between the adjacent data blocks, and the pulse generating means generates a pulse corresponding to the traveling distance of the magnetic tape.
The IBG counter counts the pulses and outputs a predetermined signal when the pulses reach a value set by the control means, and the travel control means causes the magnetic tape to travel in accordance with the output of the IBG counter. The check counter counts the pulses while the magnetic tape is running in the no-signal section, and outputs a predetermined signal when the running distance corresponding to the reference IBG distance is counted. When the control means detects the start of a no-signal period on the magnetic tape, it sets the IBG counter to a predetermined value that exceeds the count value corresponding to the reference IBG distance, and starts counting the pulses. By detecting the presence of the gap based on the output of the check counter and receiving the output of the IBG counter, the traveling control means stops the magnetic tape, and then moves the magnetic tape in the opposite direction to a predetermined direction. This is achieved by a magnetic tape device position control system characterized in that it is configured to travel a distance and stop at the center of the gap.

[Effect]

By the magnetic tape device position control method of the present invention,
When the end of a data block is detected when reading the magnetic tape, continue running the magnetic tape, check whether the distance of the no-signal section satisfies the standard IBG distance, and check whether the IBG is normal based on the result. Only when it can be determined, the tape is stopped as an IBG, and the tape is returned to its original position and stopped at the center of the IBG. Therefore, misidentification of the IBG can be prevented and subsequent data block processing can be facilitated.

〔Example〕

FIG. 6 is a block diagram of a capstan control circuit showing an embodiment of the present invention. The operation will be explained with reference to FIG.

FIG. 5 is an explanatory diagram of magnetic tape running speed and direction for position control corresponding to magnetic tape data block and IBG. For convenience of explanation, the magnetic tape MT shown in the top row of the diagram is arranged from left to right in the diagram. When the vehicle is moving, it is assumed to be traveling in the forward direction.

In the magnetic tape MT shown in Figure 5, a pseudo
When the signal deteriorates at the beginning of the PIBG, which is the IBG, the signal input level from the read head 12 in _FIG . (DB) becomes a lower signal level (this is called a low level) than the specified signal level (this is called a high level).

The check counter circuit shown in Figure 6 (hereinafter referred to as CNT2)
11, when the S _CON input is at high level, the counting operation is locked and the count value is reset to 0, and while it is at low level, the QTP signal pulse (rotation information with the same function as the conventional example shown in Fig. 1) is output. (input from the unit 6), and outputs the CRY2 signal when the count value (for example, 120) corresponding to the reference IBG distance is reached.

At the point on the MT in FIG. 5, the target circuit 10 in the control circuit 8 in _FIG . Set and count QTP signal pulses to reference IBG
The CRY1 signal is transmitted at a distance value that slightly exceeds the distance (in this example, 5QTP signal pulses).
The CRY1 signal is similar to the conventional IBGC signal.

The value to be set is, for example, according to the example of the reference IBG distance 120 explained with reference to FIG. 4, 120+5=
Set 128-125=3 to CNT19 so that the count value becomes 128 with 125 QTP signal pulses.
Making it a little larger than the standard IBG distance is the actual
This is to cover variations in IBG distance.

CNT2 11 in Figure 6 starts counting QTP signal pulses in the same way at the point on the MT in Figure 5, but when the tape runs to the point on the MT, the PIBG ends and the information signal at the normal level is output. Therefore, a high level S _CON signal is sent from the detection circuit 13 in FIG. 6 to the control circuit 8 and
CNT211 is cleared and the counting operation is locked.

In control circuit 8, at the end of this PIBG,
Since it does not receive the CRY2 signal from CNT2 11, it is determined that it is a pseudo IBG, and CNT
1 Clears 9, cancels processing for IBG, and returns to data block reading operation.

When the tape runs to the point on the MT in Figure 5, the data block ends, and the IBG begins, the same control operation as at the previous point is performed.
CNT1 9 and CNT2 11 start counting operation.

This time it is a normal IBG, so when the tape runs to the IBG end point in Figure 5, it passes the standard IBG distance near this point and moves from CNT2 11 to CRY2.
A signal is sent.

The control circuit 8 indicates that the IBG has ended and there is no signal anymore if there is the next data block.
It is detected by the high level of S _CON , but it is already CRY.
By receiving the CNT1 signal and holding it in the discrimination circuit 14, as in the case of the PIBG,
Never clear 9, continue counting,
A little past IBG, from CNT1 9 at the point shown in the running speed time chart "RUN" in Figure 5.
The CRY1 signal will be received, and the stop control process will be started using the CRY1 reception as a trigger.

In this stop control, the tape is linearly decelerated and stopped as shown by the blank line in the "RUN" chart in FIG.

When the point is reached, the midline circuit 15 is activated by the correction sequence circuit 16 in FIG.
By setting the required value in 9 to control the running distance of the tape, the tape accelerates to run in the opposite direction to the point , and then runs to the point , as shown in the "RUN" chart in Figure 5. Then, the magnetic tape MT is controlled to be decelerated until the center position of the IBG of the magnetic tape MT comes to the position of the read head 12 shown in FIG. 6, and then stops.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, it is confirmed whether the no-signal section satisfies the predetermined IBG distance with respect to the pseudo IBG that occurs on the magnetic tape by running the magnetic tape to the end of the IBG. By performing stop control, it is possible to prevent malfunctions of the magnetic tape device, and the magnetic tape is returned from a position slightly past the end of the IBG to always stop at the center of the IBG, making it difficult to read subsequent data blocks. During operation, the data read time after starting the tape can be maintained at a suitable constant time, making control easier. Therefore, it has a significant industrial effect of improving the reliability of information processing operations, improving device operation efficiency, contributing to a reduction in information processing costs, and improving the integrity of information processing contents.

[Brief explanation of drawings]

Figure 1 is a block diagram showing an example of the capstan control circuit of a conventional device, Figure 2 is a diagram of the principle of a capstan motor, Figure 3 is a diagram showing a capstan tacho pulse time chart, and Figure 4 is how to make a conventional IBG. FIG. 5 is an explanatory diagram of the operation of the embodiment of the present invention, and FIG. 6 is a block diagram of the embodiment of the present invention. In the figure, 1 is a capstan motor section, 2 is a capstan motor, 3 is a tachometer, 4 is a capstan, 5 is a capstan drive section, 6 is a rotation information section, 7 is a capstan logic circuit section, 8 is a control circuit, 9 is the IBG counter circuit (CNT1),
10 is a target circuit, 11 is a check counter circuit (CNT2), 12 is a read head, 13 is a detection circuit, 14 is a discrimination circuit, 15 is a median circuit, and 16 is a correction sequence circuit.

Claims (1)

[Scope of Claims] 1. A magnetic tape device, comprising a pulse generation means, an IBG counter, a travel control means, a check counter, and a control means, the magnetic tape device writes data blocks on a magnetic tape. When recording, a gap is provided between the adjacent data blocks by a reference IBG distance, and the pulse generating means generates a pulse corresponding to the traveling distance of the magnetic tape, and the pulse generating means generates a pulse corresponding to the traveling distance of the magnetic tape, and counts the pulses and outputs a predetermined signal when the pulses reach a value set by the control means, and the travel control means determines the end of travel of the magnetic tape in accordance with the output of the IBG counter. and the start of the magnetic tape, and the check counter counts the pulses while the magnetic tape is running in the no-signal section, and
When the running distance corresponding to the IBG distance is counted, a predetermined signal is output, and when the control means detects the start of a no-signal section of the magnetic tape, it outputs a predetermined signal to the IBG counter.
By setting a predetermined value exceeding the count value corresponding to the IBG distance to start counting the pulses, detecting the presence of the gap by the output of the check counter, and receiving the output of the IBG counter, A magnetic tape device position control system characterized in that, after the magnetic tape is stopped by the running control means, the magnetic tape is run a predetermined distance in the opposite direction and stopped at the center of the gap. .