JPH0127502B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive method for a magnetic tape (hereinafter simply referred to as tape) for the purpose of recording and reproducing data, and in particular, the present invention relates to a drive method for a magnetic tape (hereinafter simply referred to as tape) for the purpose of recording and reproducing data, and in particular, the present invention relates to a drive system that accommodates the performance of a reel motor including a drive unit and the tape buffer length. The present invention relates to a drive system that allows the tape to run at higher speeds without changing the capacity of the column.

In recent years, with the development of computer systems, magnetic tape devices are increasingly being used as back amplifiers for magnetic disk devices. In this case, it is naturally required to quickly transfer data between the two devices, but since the recording format on the tape is determined by standards on the magnetic tape device side, the recording,
To increase the playback speed, the tape running speed must be increased. Therefore, the magnetic tape device is required to be configured to have a dual running speed capable of recording and reproducing at high speeds as well as normal speeds.

When recording and playing back tape by running it at high speed, the system that repeats running/stopping for each data block, which is used when running at low speed, requires excessive specifications for the reel drive system, so streaming mode is used. A method called ``will be adopted.

In this streaming mode, the recording format on the tape is the same as before, but the tape is recorded or played back while running continuously at a much higher speed than in the start-stop mode. Even in this method, if a retry becomes necessary, the running of the tape must be reversed.

Normally, in a magnetic tape device, the inertia of the reel system is extremely large compared to the capstan system, and it is almost impossible to make the acceleration characteristics of the two the same when starting/stopping tape running. A buffer mechanism that accommodates a slack portion called a tape loop is provided between the two to absorb this unevenness in acceleration performance.

FIG. 1 shows the state at low speed. There is a tape loop 4 between the capstan 1 and the reel 2, which is the supply side when running in the forward direction, and there is also a tape loop 4 between the capstan 1 and the reel 2 on the take-up side. There is a loop 4'. Both loops are housed in vacuum columns 5 and 5', respectively, as damping mechanisms. Since the length of this loop portion, that is, the buffer length, uniquely corresponds to the tape position within the column, in the following explanation, the buffer length at that time will be indicated according to the loop position within the column.

FIG. 2 shows a graph of the loop position and its displacement speed when starting, stopping, or reversing at a normal tape speed. In the same graph, the horizontal axis is the tape position in the column, and points _B1 to _B5 are _B1 in Figure 1.
~ Corresponds to _B5 . Further, the vertical axis is the speed at which the loop is rising or falling, and when it is rising, it is in the positive direction.

When the tape is at rest, the loop 4 in column 5 is in the central position _B3 , which corresponds to point _B3 on the graph of FIG. At start-up, the rotation of the capstan almost instantaneously reaches constant speed Vc, whereas in normal start/stop mode the reel starts with a delay, so loop 4 in column 5 rises at a speed of Vc/2. Become.

In other words, it will move to point _A on the graph.

The reel drive starts when the loop reaches the _B2 point. The difference L in tape feed amount that occurs until the reel is accelerated and reaches Vc is the buffer length, and the intervals between Bn and Bn+ ₁ in the column are both set to a length corresponding to this L, so When the reel speed reaches constant speed Vc, the loop is in position _B1 .

The situation during this period corresponds to the movement of A ₁ to A ₂ to B ₁ on the graph. That is, the loop rises at a constant speed of Vc/2 until the reel starts and reaches point _B2 , and as the reel accelerates, it stops at point _B1 . The movement of the loop 4' in the other column 5' can be understood in exactly the same way, with the only difference being that the loop 4 is ascending while this is descending.

Next, consider the case where the tape running is reversed from this state. As soon as the direction of rotation is switched, the capstan starts rotating at a constant speed of −Vc, but
Since the reel has a large inertia, it continues to rotate in the forward direction while decelerating. That is, immediately after switching, since the tape is fed out from both the capstan and the reel at Vc on the column 5 side, the loop 4 begins to descend at a speed of -Vc. In the graph of Figure 2, this corresponds to moving to point _A3 .

The reel is driven in the direction of stopping and reversing, but assuming that the braking and driving torques are the same,
In this case, this corresponds to a relative acceleration of 2Vc, so if controlled using the linear servo method, a buffer length of 4L is required. In other words, when it corresponds to the movement of the loop,
When the loop drops to _B4 , the reel stops rotating, immediately starts reversing, and when it reaches a constant speed of -Vc, the loop comes to rest at _B5 . The graph moves from A ₃ to B ₅ .

When inverting again, the same thing is done, except that the loop rises and falls. This corresponds to a transition of B ₅ -A ₄ -B ₁ in the graph.
From this situation, if the tape speed Vc is
The capacity of the column is usually designed to accommodate a buffer length of 4L.

If we consider that a device designed for the start/stop mode described above is to be used in a faster, say 2x, streaming mode, the capstan speed and reel speed would have to be doubled. Of course, unless the driving and braking torque of the reel system is changed, a column capacity of 16L will be required for a tape speed of 2Vc.

The present invention solves this problem by controlling the timing of capstan reversal, and provides a dual-speed system that enables high-speed running up to twice the speed with the same reel drive system and column capacity as conventional equipment. It provides a magnetic tape drive system, and when running a magnetic tape at high speed, first only the reel motor is driven, and after applying a predetermined bias to the tape loop position, the capstan motor is driven. It is said that

As a first example, a case will be described in which the tape is run at twice the speed and reversed.

FIG. 3 is a block diagram of an apparatus for carrying out the invention. When a start signal is sent to a device in a stopped state, the reel control circuit 7 first operates and starts the reel drive circuit 8 in accordance with the high speed/low speed.
Loop 4 in column 5 when stopped in slow mode
is at the central position, ie B ₃ . When a high speed mode command is received, the reel 2 rotates and the loop 4 descends within the column. When the loop 4 reaches _B5 , the reel control circuit 7 receives a signal from the loop position detection circuit 6 and sends a signal to the high-speed capstan control circuit 10, which activates the capstan drive circuit 9, but at the same time the reel drive circuit It also operates at high speeds.

The capstan immediately reaches a constant speed of 2Vc, but in order to absorb the delay in acceleration on the reel side, a buffer length of 4L is required as described above, so when reel 2 reaches constant speed, loop 4's The location is _B1
It's on the rise.

When a signal to reverse the tape running is sent, the high-speed capstan control circuit 10 temporarily stops the capstan 1 and does not immediately start rotating in the opposite direction. On the other hand, the reel is also braked at the same time, but a buffer length of 4L is required even for the deceleration of 2Vc, and the reel stops when the position of loop 4 reaches _B5 .

Next, rotate reel 2 in the reverse direction, and loop 4
Raise the position to B ₁ . When it detects that the loop has risen to B ₁ , a signal is sent, similar to when driving in the forward direction, and the capstan and both reels begin to rotate in the opposite direction. At this time as well, a buffer of 4L is required until the reel speed reaches -2Vc, and when the loop in column 5 drops to _B5 , tape running becomes steady.

When it is reversed again and run in the forward direction, the movement of the loop in the column is reversed, but the timing of stopping and starting the capstan is the same.

FIG. 4 is a graph showing the movement of loop 4 in the above operation. First, at startup, B ₃ -B ₄ -
Bias the loop position with B ₅ and start the capstan with 2Vc. The loop rising speed at this time is
Since it is Vc, the graph moves to A ₁ ', and as the reel accelerates, it moves to B ₁ , and when the reel speed reaches 2Vc, the loop 4 stops at B ₁ .

When reversing, the capstan stops, so loop 4 starts descending at -Vc. In other words, it becomes A ₃ '. Braking is applied to the reel, and loop 4 drops by 4L and stops at _B5 , but the reel motor starts to reverse, and when the loop rises and reaches _B1 , the capstan starts rotating at -2Vc. loop 4
The state changes again to A ₃ ′, and then to B ₅ , where steady running in the opposite direction begins. B ₅ when inverting again
-A ₁ '-B ₁ is repeated twice, and steady running begins at B ₁ . As described above, the operation of loop 4' in column 5' is similar to that of loop 4'.

If controlled using the method described above, even if the reel drive system is the same as before, it will be possible to start, stop, and reverse at twice the speed with a 4L column capacity.

The method of the present invention is not only applicable to 2Vc, but can also be applied to any high-speed running up to 2Vc by simply adjusting the amount of bias applied to the loop position. Since a unique effect is produced when the running speed is √2Vc, a case where the vehicle is driven at high speed at √2Vc will be explained as a second embodiment.

As in the normal case, the position of loop 4 at startup is
_B3 . In this embodiment, capstan activation and reel activation are started at the same time. Naturally, loop 4 starts to rise in column 5, but the constant speed is √2
Since it is Vc, the delay in acceleration of the reel is absorbed by the movement of 2L, and when it enters steady running, loop 4 becomes B ₁
It is in. The situation during this time is shown in the graph in Figure 5 as B ₃ -
This corresponds to the transition A ₁ ″−B ₁ .

In the case of a stop, if the capstan is stopped and the reel is braked, the opposite situation will appear when accelerating.
Loop 4 returns to _B3 and the reels stop. The situation during this period corresponds to B ₁ - A ₃ ″ - B ₃ in the graph of Figure 5.

In this way, it starts from B ₃ and stops at B ₃ , so in case of reversal, wait for the reel to stop,
That is, it is sufficient to wait for the loop to return to _B3 and then start driving the capstan and reel in the opposite direction, and it is not necessary to apply a bias to the loop position.

As explained above, according to the present invention, it is possible to switch the tape running speed within a speed range of up to twice the speed with the same tape buffer length without increasing the torque of the reel drive system.

[Brief explanation of drawings]

1 and 2 are diagrams for explaining the tape buffer in low-speed mode, and FIGS. 3 to 5 are diagrams for explaining the present invention, in which 1 is a capstan;
1' is a capstan motor, 2 and 3 are reel or reel motors, 4 and 4' are tape loops, 5,
5' is a column, 6 is a loop position detection circuit, 7 is a reel control circuit, 8 is a reel drive circuit, 9 is a capstan drive circuit, 10 is a high speed capstan control circuit, and 11 is a low speed capstan control circuit.

Claims (1)

[Claims] 1. A tape buffer length in a magnetic tape drive of a magnetic tape device that has dual magnetic tape running speeds of high and low speeds and is capable of recording and reproducing data at either speed. and reel motor system drive/
The braking torque is set according to the low-speed running mentioned above, and when reversing the tape during low-speed running, use the following.
When selecting control (a) and reversing the tape while it is running at high speed, use the following:
A magnetic tape running reversal system characterized by selecting the control of (b). (a) Control that drives the capstan motor and reel motor immediately and simultaneously in opposite directions. (b) After immediately stopping the capstan motor and starting to drive the reel motor in the opposite direction, from the time when the reel motor starts to be driven in the opposite direction,
The capstan is operated after a period of time, which is set as a point in time from when the capstan starts to be driven in the opposite direction until the tape loop displacement that occurs until the reel speed matches the tape speed, no longer exceeds the capacity of the tape buffer, Control to start driving the stun motor in the opposite direction.