JPS6350780B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic tape device having a vacuum column which is a buffer mechanism for enabling rapid start-up and stop of a magnetic tape, and more particularly, to An air valve to bring the inside of the column from a negative pressure state (called vacuum) to above atmospheric pressure (called pressure) when unloading the column (to take out all the magnetic tape in the column). Even when the unit does not switch, the column out failure alarm (unit check when the unloading operation is not completed within the specified time due to time monitoring) will not occur, and other operations will not occur. The present invention relates to a magnetic tape device that enables reliable column out during unloading without inducing secondary failures.

Generally, the reel control mechanism in such a magnetic tape device detects the tape position in the vacuum column with a tape position detector, and uses changes in the output signal to obtain the tape loop position, moving direction, and moving speed, and then controlling the motor drive circuit. A control signal is applied to the motor to drive the motor, and the tape loop position within the vacuum column is controlled to always be within a predetermined range.

Therefore, while the tape is running, the tape loop is controlled so that it is always located at the center of the vacuum column.

Generally, such a state in which the position of the tape loop is controlled is called a servo ON state, and the motor drive operates in a constant current mode that controls the current.

In a magnetic tape device that performs this kind of control, it is necessary to wind up the tape from a vacuum column in order to unload the magnetic tape, and this operation is called column out. In this state, the tape loop It is necessary to disable the signal feedback from the position detector, turn off the servo, and drive the reel motor in a constant voltage mode that drives it at a constant rotation.

This switching from servo ON to servo OFF is
It is automatically switched by a signal from a vacuum switch that detects the pressure inside the vacuum column. That is, when the vacuum switch is detecting negative pressure (vacuum), the servo is on, and when it is detecting atmospheric pressure or higher (pressure), the servo is off.

A method of controlling column out in a conventional magnetic tape device will be explained below.

Switch the air valve on the path that supplies vacuum to the vacuum column to stop the negative pressure supply and bring the column to atmospheric pressure.

When the pressure inside the column exceeds atmospheric pressure, the vacuum switch detects this and switches the reel control to the servo OFF state.

At the same time, a winding signal is applied to the reel motor control circuit, causing the reel to rotate at a constant rate and winding up the tape. Continue to wind up the tape in the other vacuum column.

The machine reel side has stopped until then because the tape is wound from both columns and rotates constantly on the file reel BWD, but due to the rotation of the file reel, it rotates to BWD (the tape is pulled and moves to BWD), Using the induced voltage constant of the machine reel, it is possible to monitor whether the tape is stretched and the thread is in the threaded state (reel loaded).

Reel loaded ON (machine reel is BWD)
When the machine reel reaches BWD at a constant rotation speed, both reels BWD wind the tape onto the file reel.

In this conventional column-out control method, if the air valve does not switch properly for some reason, the pressure inside the column will not rise above atmospheric pressure, so the vacuum switch will not operate and the reel control servo will not operate. It will not switch to the OFF state.

When the servo is not turned OFF and the servo is ON, the reel control is performed so that the tape loop is always located within the column, so even if a tape winding signal is applied to the reel motor drive circuit, it becomes invalid and tape winding becomes impossible. , an alarm is generated because the tape winding is not completed within the specified time.

Another disadvantage is that if the inside of the column suddenly becomes atmospheric pressure, the tape may be wound up rapidly or the tape may be wound loosely, causing damage to the tape such as Z-folds.

The present invention solves the above-mentioned problems of conventional magnetic tape devices. In other words, even if the valve system that switches the air system from vacuum pressure to pressure pressure during unloading is defective or malfunctioning and cannot be completely switched, the reel servo's constant current mode can be switched from the reel servo's constant current mode to the constant voltage mode that drives the reel at constant rotation, and the unloading can be performed. We provide a magnetic tape device that prevents alarms from occurring, prevents secondary failures such as tape Z-folding and tape stretching due to valve defects or malfunctions, and enables reliable and reliable unloading. It is intended to.

The present invention also provides a vacuum column for rapidly starting and stopping a magnetic tape, a switch for switching the supply of air into the column, and a vacuum switch for detecting the pressure within the column. Only when the vacuum switch is detecting negative pressure, the tape loop position and tape movement speed are detected by the tape loop position detection circuit and tape movement speed detection circuit in the vacuum column, and are fed back to the reel drive control circuit to constantly monitor the column. a reel servo mechanism that controls the current supplied to the reel motor so as to maintain the tape position within a certain range; the magnetic tape device winds up the tape in the column to unload the magnetic tape; In this case, the tape loop position detection circuit, the tape movement speed detection circuit, and
This is achieved by a magnetic tape device characterized in that a means for reducing the gain of the reel drive control circuit is provided.

That is, in the present invention, when column-outing the tape loop during unloading, the air valve is If the reel servo control has a low gain even if the servo is not switched properly and the servo remains ON, the tape winding operation will be prioritized over the control to position the tape loop in the center of the column, so the tape will not be wound normally from the column. It becomes possible.

When the tape is completely wound up from the vacuum column, the inside of the column becomes atmospheric pressure and the servo is completely switched off.

Furthermore, in the present invention, the number of reel rotations is reduced while the tape is wound from both columns.

Embodiments of the magnetic tape device according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of the main part (reel motor drive circuit) of the magnetic tape device according to the present invention. It has a function to drive the reel motor at a constant rotation speed during loading and unloading.

Here, when performing tape loop column out from the servo-on state during unloading, the gains of the loop position detection circuit 1 and the moving speed detection circuit 2 are switched by the gain switching circuit 3, and the gain of the constant current detection circuit 4 is switched by the gain switching circuit 5. After switching, the reel motor 6 is set to constant voltage mode, and the tape loop 7 is moved out of the column. After winding up the tape from one column 8, the gain of the constant voltage detection circuit 9 is switched by the gain switching circuit 10, and the reel motor 6 is rotated at two speeds, and when the tape is wound up from both columns and the tape detects reel loading. , the file and machine reel are rotated to BWD, and the tape is wound onto the file reel 11.

In the above process, if the valve is defective or malfunctions and the inside of the column 8 is not completely switched to the pressure mode and the column is pulled by the vacuum, the servo will remain in the constant current mode servo-on state even if the column is switched to the constant voltage mode. It becomes invalid and stops with a tape loop formed on the column, and after a certain period of monitoring, an alarm occurs, or when the tape loop on the machine side is pulled by air and moves to the bottom of the column, the machine reel rotates to BWD and reel loading is detected. Because both reels BWD rotate with tape loops formed on both the file and machine columns, Z-folds occur on the data surface, damaging the data or causing the tape to stretch.

In the present invention, the gains of the loop position, moving speed detection circuits 1 and 2, and current detection circuit 4 are lowered when the column is out, and the gain of the voltage detection circuit 9 is lowered when switching to the constant voltage mode.
Since it is driven by BWD, even if the valve is not switched and is in constant current mode, you can easily column out the tape loop without generating unnecessary alarms.

In the magnetic tape device according to the present invention, when the tape is then wound up from one column, the gain of the constant voltage mode is increased again, the reel rotational speed is lowered, and the tape is wound at a low speed such that the tape does not stretch until the reel load is detected. Try to take it.

As has become clear from the above embodiments, in the present invention, if the air switching system is defective or malfunctions,
There is no unnecessary alarm, and even if the machine side tape loop is pulled by the air and moves to the bottom of the column, the machine reel does not rotate to BWD, and reel loading is not detected here, so the file and machine column are Both reels will not rotate BWD while forming a tape loop.

Therefore, unnecessary alarms during unloading can be reduced, and in addition, tape Z breaks, tape stretching,
Secure and reliable unloading is possible without secondary failures such as disconnection.

In Fig. 1, 12 is a loop sensor receiving circuit, 13 is a vacuum switch receiving circuit, 14 is an addition amplifier circuit, 15 is a reference voltage generation circuit, 16 is a drive control circuit, 17 is a constant current comparator, and 18 is a constant voltage A comparator, 19 is a motor drive power amplifier, 20 is a current detection resistor, connections shown by broken lines are used for column out during unloading, and 20 is a gain switching signal.

Furthermore, in the above embodiment, a method was described in which the gain is switched from the beginning when performing column out, but the application of the present invention is not limited to this. It is also possible to switch the gain again when the post-unloading is not completed.

[Brief explanation of drawings]

FIG. 1 shows an embodiment according to the present invention, in which 1 is a loop position detection circuit, 2 is a loop movement speed detection circuit, 3, 5, 10 are gain switching circuits, 4 is a current detection circuit, and 6 is a loop movement speed detection circuit. Reel motor, 7 tape loop, 8 vacuum column, 9 voltage detection circuit, 11 reel, 12 loop sensor reception circuit, 13 vacuum switch reception circuit, 14 summing amplifier circuit, 15 reference voltage generation circuit, 16 is a drive control circuit, 17 is a constant current comparator, 18 is a constant voltage comparator, 19 is a motor drive comparator, 20 is a gain switching signal, and 21 is a linear sensor.

Claims (1)

[Scope of Claims] 1. A vacuum column for rapidly starting and stopping a magnetic tape, a switch for switching the supply of air to the column, a vacuum switch for detecting the pressure within the column, and the vacuum. Only when the switch is detecting negative pressure, the tape loop position and movement speed are detected by the tape loop position detection circuit and tape movement speed detection circuit in the vacuum column, and are fed back to the reel drive control circuit. A reel servo mechanism that controls current supplied to the reel motor so as to maintain the tape position within a certain range; , the tape loop position detection circuit, the tape movement speed detection circuit, and
A magnetic tape device comprising means for reducing the gain of the reel drive control circuit.