JPH02198055A - Pneumatic pressure control system for magnetic tape device - Google Patents

Abstract

PURPOSE:To make the floating quantity of a magnetic tape constant and to prevent the occurrence of hinging by providing a means commanding the adjustment of a pneumatic pressure to an air supply section and keeping the pneumatic pressure supplied by the air supply section within a normal range. CONSTITUTION:An indicating means 17 is operated by a signal opening a shutter 3 coming from a terminal A and compares an amplitude of an analog signal read by a magnetic head 1 with a predetermined upper limit and lower limit respectively. When the amplitude is larger than the upper limit as the result of comparison, the means 17 gives an indication to an air supply section 7 to increase its pneumatic pressure and when the amplitude is lower than the lower limit, the means 17 gives an indication to decrease the pneumatic pressure thereby controlling the air supply section 7 in a way that the amplitude of the analog signal resides within the upper limit and the lower limit. Through the constitution above, it is possible to make the floating quantity of the magnetic tape 2 constant, and since the tension of the magnetic tape 2 is kept to a constant value, the production of hinging of the magnetic tape is prevented.

Description

[Detailed Description of the Invention] [Summary] The present invention aims to improve the reliability of an air pressure control method for a magnetic tape device that detects the flying height of a magnetic tape levitated by an air lifter function and controls the air pressure to be constant. The air lifter function uses the air pressure supplied by the air supply unit to levitate the magnetic tape above the magnetic head, and when the air pressure inside the tension sensor falls below the standard value, the tension on the magnetic tape is increased and the tension is increased. A magnetic tape device equipped with a tension servo circuit that controls the tension of the magnetic tape to be constant based on a control signal that instructs to weaken the tension of the magnetic tape when the air pressure inside the sensor rises above a reference value. When the air lifter function is activated, if the amplitude of the analog signal read by the magnetic head from the magnetic tape with constant tension floating above the magnetic head exceeds the predetermined upper limit or lower limit, the air supply section An instruction means is provided to instruct the air pressure to be adjusted, and when the amplitude of the analog signal becomes larger than the upper limit value, the air supply unit is instructed to increase the air pressure, and when the amplitude of the analog signal becomes greater than the lower limit value. When the air pressure becomes smaller, the air supply unit is instructed to lower the air pressure, and the amplitude of the analog signal is controlled to be between the upper limit and the lower limit while the air lifter function is in operation.

[Industrial application field]

The present invention relates to a magnetic tape device equipped with an air lifter function that uses air pressure to levitate a magnetic tape above a magnetic head, and a tension servo circuit that uses changes in air pressure to control the tension of the magnetic tape. The present invention relates to an air pressure control method for a magnetic tape device that detects the flying height of a magnetic tape floating by an air lifter function and controls the air pressure to be constant.

A magnetic tape device writes/reads data by bringing the magnetic tape into contact with a magnetic head, but when rewinding the magnetic tape or performing a search to drive the magnetic tape to a predetermined data block position, In addition to running the magnetic tape at high speed, it also has an air lifter function that blows air near the magnetic head to prevent the magnetic tape from coming into contact with the magnetic head, and uses this air pressure to lift the magnetic tape above the magnetic head. A tensioner that blows air onto the magnetic tape in contact with the sensor, detects the degree of adhesion of the magnetic tape to the tension sensor, that is, the tension of the magnetic tape, based on fluctuations in air pressure within the tension sensor, and controls this tension so that it remains constant. Some are equipped with servo circuits.

This is done in order to avoid unnecessary contact between the magnetic tape and the magnetic head, thereby reducing damage to the magnetic tape and dirt on the magnetic head, and also when winding the magnetic tape onto a machine reel or file reel. If the magnetic tape is not wound with the tension of This is to prevent such phenomena from occurring, such as when the magnetic tape winds up abnormally and the data is destroyed.

Therefore, in order for the air lifter function and the tension servo circuit to operate normally, it is necessary that the air pressure within the pipe is always constant.

[Conventional technology] FIG. 5 is a diagram explaining the conventional technique.

The magnetic tape 2 unwound from the file reel 9 comes into contact with the magnetic head 1 along the guide 11, and then comes into contact with the magnetic head 1 on the guide 11.
2 along the machine reel 8 via the tension sensor 10
It is set so that it will be wound up.

Based on the control of the host device, the magnetic tape device instructs the tension servo circuit 14 to drive the machine reel motor 15 and file reel motor 16 to unwind the magnetic tape 2 from the file reel 9 and onto the machine reel 8. At the same time, data is sent to the magnetic head 1 via a write circuit (not shown) to write the data onto the magnetic tape 2, and the magnetic head 1 reads data from the magnetic tape 2 by a read circuit (not shown). Send the data to the host device.

The magnetic tape device receives magnetic tape 2 from the host device, for example.
When instructed to rewind, the air lifter function is activated. That is, the shutter 3 is opened, the air in the vibrator 5 is blown out from the outlet 4, and this air pressure is used to float the magnetic tape 2 away from the magnetic head l. Then, the machine reel motor 15 and file reel motor 16 are driven via the tension servo circuit 14 to rotate the machine reel 8 and file reel 9 at high speed to run the magnetic tape 2 at high speed. Let it wind up.

At the same time, air is supplied from the pipe 5 to the tension sensor 10, and the air supplied to the tension sensor 10 is blown out against the magnetic tape 2. The air pressure within the tension sensor 10 changes from the reference value in response to the tension. The pressure conversion circuit I3 detects a pressure change exceeding the allowable range from this reference value, converts it into, for example, a positive or negative electrical signal, and sends it to the tension servo circuit 14.

The tension servo circuit 14 is a file reel motor 16
is strongly driven in the direction in which the magnetic tape 2 is wound onto the file reel 9, and the machine reel motor 15 is driven weakly in the direction in which the magnetic tape 2 is wound onto the machine reel 8, thereby rotating the magnetic tape 2 in the reverse direction. Tension is applied to the magnetic tape 2 by pulling the magnetic tape 2, causing the file reel 9 to wind the magnetic tape 2. At this time, the positive current sent out by the pressure conversion circuit 13 is connected to a negative electrical signal, for example, by a machine reel motor. The driving force 15 is controlled so that the tension of the magnetic tape 2 is always constant.

That is, when the pressure inside the tension sensor 10 is higher than the reference value, it is determined that the tension of the magnetic tape 2 is too strong, and when the pressure inside the tension sensor 10 is lower than the reference value, it is determined that the tension of the magnetic tape 2 is too weak. The driving force of the machine reel motor 15 is adjusted so that the pressure is within an allowable range with respect to the reference value.

At this time, the air supply unit 7 is sending air within a predetermined pressure range to the pipe 5, and this pressure is monitored by the air pressure sensor 6. If the pressure falls outside the predetermined range, the air supply unit 7 7 will be notified.

Therefore, the air supply section 7 always sends air within the pressure range detected by the air pressure sensor 6 to the pipe 5.

Further, when the magnetic tape device receives a search instruction from the host device, for example, it operates the air lifter function and also causes the machine reel motor 15 to move the magnetic tape 2 to the machine reel 8.
The file reel motor 16 is driven strongly in the direction in which the magnetic tape 2 is wound, and the file reel motor 16 is weakly driven to rotate in the opposite direction to the running direction of the magnetic tape 2 to apply tension to the magnetic tape 2. As described above, the tension of the magnetic tape 2 is controlled so that the tension is within the allowable range with respect to the reference value.

[Problem to be solved by the invention]

As mentioned above, when the magnetic tape 2 is run at high speed, such as when rewinding the magnetic tape 20 or searching, conventionally the flying height and tension of the magnetic tape 2 are indirectly controlled by the air pressure inside the vibrator 5. Therefore, if the air pressure in the pipe 5 deviates from the normal value due to a failure in the air pressure sensor 6 or air leaking from the pipe 5, the tension sensor 1
If the reference value of the air pressure within 0 deviates, the electric signal corresponding to the pressure change detected by the pressure conversion circuit 13 will become an erroneous control signal because the reference is deviated, and the tension of the magnetic tape 2 will become too strong. If the magnetic tape becomes too weak, hinching may occur in the wound magnetic tape, causing damage to the magnetic tape 2 or data destruction due to abnormal winding.

Then, as the pressure of the air blown out from the air outlet 4 changes, the tension of the magnetic tape 2 also changes, so the air lifter function is not fully exerted, and the magnetic tape 2 running at high speed comes into contact with the magnetic head 1. If this happens, the magnetic tape 2 may be damaged or the magnetic head 1 may become dirty.

As described above, the conventional pneumatic control system for magnetic tape devices has a problem of poor reliability.

In view of these problems, an object of the present invention is to monitor the flying height of the magnetic tape 2 with respect to the magnetic head 1, thereby controlling the air pressure, thereby improving reliability.

[Means to solve the problem]

FIG. 1 is a block diagram of the principle of the present invention, and FIG. 2 is a diagram explaining the operation of FIG. 1.

The same reference numerals as in FIG. 5 indicate the same functions. When the host device instructs the magnetic tape 2 to be rewound, the magnetic tape device operates the air lifter function as described above. That is,
A signal to open the shutter 3 is input from the terminal A, the shutter 3 is opened, air from the pipe 5 is blown out from the outlet 4, and the magnetic tape 2 is floated above the magnetic head 1.

Further, as described above, the machine reel motor 15 and the file reel motor 16 are driven via the tension servo circuit 14, and the magnetic tape 2 is wound from the machine reel 8 onto the file reel 9.

Therefore, the data read from the magnetic tape 2 on which the magnetic head 1 floats becomes an analog signal and is sent to the instruction means 17. As shown in FIG. 2, the amplitude of the analog signal at this time changes in accordance with the flying height of the magnetic tape 2 from the magnetic head 1, with the horizontal axis representing the flying height and the vertical axis representing the amplitude.

That is, as the distance between the magnetic head 1 and the magnetic tape 2 increases, the amplitude of the analog signal of the data read by the magnetic head 1 becomes smaller. The larger the value, the lower the air pressure inside the pipe 5.

The instruction means 17 is operated by a signal from the terminal A to open the shutter 3, and compares the amplitude of the analog signal read by the magnetic head 1 with a predetermined upper limit value and lower limit value. When the amplitude of the analog signal exceeds the upper limit and increases, an instruction is sent to the air supply unit 7 to increase the air pressure, and when the amplitude of the analog signal exceeds the lower limit and decreases, the air supply unit 7 is instructed to increase the air pressure. The air supply unit 7 is controlled so that the amplitude of the analog signal is between the upper limit value and the lower limit value.

That is, on the horizontal axis of FIG. 2, if the range in which the magnetic tape 2 is floating due to normal air pressure is between . On the vertical axis of Figure 2, it is between ■ and ■.

Therefore, the upper limit value becomes ■, and the lower limit value becomes ■.

As described above, the instruction means 17 controls the air supply unit 7 so that the amplitude of the analog signal exists between ■ and ■.
The flying height of the magnetic tape 2 is maintained at a normal value, and the air pressure within the tensile sensor 10 is also maintained at a normal value. Therefore, the pressure conversion circuit 13 detects changes in the tension of the magnetic tape 2 using normal air pressure and controls the tension servo circuit 14, so that the tension of the magnetic tape 2 can be maintained at a normal value.

[Effect]

With the above configuration, the indicating means 17 maintains the air pressure supplied by the air supply section 7 within a normal value range. Therefore, the magnetic tape 2 running at high speed is transferred to the magnetic head 1.
Since the pneumatic pressure control method of the magnetic tape device can be improved, the reliability of the pneumatic control method of the magnetic tape device can be improved because the magnetic tape device is not damaged by contact with the magnetic tape device and the occurrence of hinching can also be prevented.

〔Example〕

FIG. 3 is a schematic diagram of a circuit showing one embodiment of the present invention, and FIG. 4 is a diagram explaining the operation of FIG. 3.

FIG. 3 is a detailed diagram of the indicating means 17 of FIG. 1. The magnetic head 1 reads data recorded on the magnetic tape 2 at a signal level inversely proportional to the distance from the floating magnetic tape 2, and converts the data into an analog signal to a preamplifier circuit 18.
The preamplifier circuit 18 amplifies this analog signal with a predetermined amplification degree and sends it to the automatic gain adjustment amplifier circuit 24 and the rectifier circuit 19.

The automatic gain adjustment amplifier circuit 24 is used in a normal data readout circuit, and the data amplified here is sent to a readout circuit (not shown). The analog signal sent to the rectifier circuit 19 is full-wave rectified and sent to the comparison circuit 20.

A predetermined upper limit value is input to the comparison circuit 20 from terminal B, and a predetermined lower limit value is input from terminal C. As shown in FIG. 3, the comparator circuit 20 receives, for example, a full-wave rectified analog signal as shown by the solid line (■), or a dotted line (■), where the vertical axis is amplitude and the horizontal axis is time. A full-wave rectified analog signal is input from the rectifier circuit 19.

Therefore, the comparison circuit 20 compares the amplitude of the input analog signal using the predetermined upper limit value ■ and lower limit value ■, and if the amplitude is as shown in ■, the magnitude exceeds the upper limit value ■. The A/D conversion circuit 2 sends a signal that increases the proportional air pressure.
1, and if the amplitude is as shown in (■), a signal is sent to the A/D conversion circuit 21 to lower the air pressure in proportion to the magnitude exceeding the lower limit (■).

The A/D conversion circuit 21 converts the signal sent by the comparison circuit 20 into a digital value and sends it to the gate circuit 22. As described above, a signal for opening the shutter 3 shown in FIG. 1 is input to the gate circuit 22 from the terminal A, and the gate is opened by this signal. Therefore, the digital value sent out by the A/D conversion circuit 21 is stored in the memory 23 and then sent out to the air supply section 7.

The air supply section 7 increases the air pressure if the digital value sent out from the memory 23 is a signal to increase the air pressure, and lowers the air pressure if it is a signal to decrease the air pressure.

Therefore, when the amplitude of the analog signal as shown in FIG. The amplitude of the analog signal obtained from the data read from tape 2 decreases and becomes lower than the upper limit ■.

The comparator circuit 20 stops sending out the signal that increases the air pressure when the amplitude of the analog signal becomes less than the upper limit value ■.
The /D conversion circuit 21 also stops sending out digital values. Therefore, since the memory 23 continues to supply the digital value at this time to the air supply unit 7, it continues to supply the air pressure corresponding to this digital value to the pipe.

Moreover, when the amplitude of the analog signal as shown in FIG.
The magnetic tape 2 comes closer to the magnetic head 1, and the amplitude of the analog signal obtained from the data read by the magnetic head 1 from the magnetic tape 2 increases and becomes higher than the lower limit (2).

The comparator circuit 20 stops sending out the signal that lowers the air pressure when the amplitude of the analog signal exceeds the lower limit value 0.
The /D conversion circuit 21 also stops sending out digital values. Therefore, since the memory 23 continues to supply the digital value at this time to the air supply unit 7, it continues to supply the air pressure corresponding to this digital value to the pipe.

Therefore, the amplitude of the analog signal sent out by the magnetic head 1 is controlled so that it exists between 2 and 3 in FIG.

〔Effect of the invention〕

As described above, the present invention makes it possible to keep the flying height of the magnetic tape constant, and also makes it possible to maintain a constant value of the air pressure sent to the pipe by the air supply section. Therefore, the tension of the magnetic tape can be maintained at a constant value, which prevents the occurrence of hinching of the magnetic tape and prevents the magnetic tape running at high speed from contacting the magnetic head and causing damage or staining the magnetic head. Therefore, a highly reliable air control system can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the principle of the present invention, FIG. 2 is a diagram explaining the operation of FIG. FIG. 5 is a block diagram illustrating an example of the prior art. In the figure, ■ is a magnetic head, 2 is a magnetic tape, 3 is a shutter, 4 is an air outlet, 5 is a pipe, 6
is an air pressure sensor, 7 is an air supply section, 8 is a machine reel, 9 is a file reel, 10 is a tension sensor, 1
1.12 is a guide, 13 is a pressure conversion circuit, 14 is a tension servo circuit, 15 is a machine reel motor, 16 is a file reel motor, 17 is an indicating means, 18 is a preamplifier circuit, 19 is a rectifier circuit, 20 is a comparison circuit 21 is an A/D conversion circuit, 22 is a gate circuit, 23 is a memory, and 24 is an automatic gain adjustment amplifier circuit. 7 U 1 Figure 1 Shigeno I and Sun Moon Village Figure 2 9 Invention /) Principle B'mouth Nq Ryo 1 / Diagram Fluency % 3 En]aF Movement I Bias ITB Monthly 1F Itotoyo 4th Exit

Claims (1)

[Claims] An air lifter function that levitates the magnetic tape (2) above the magnetic head (1) using the pressure of the air supplied by the air supply section (7); If the air pressure in the tension sensor (10) that is supplied with is lower than the reference value, an instruction is given to increase the tension of the magnetic tape (2), and the air pressure in the tension sensor (10) is lower than the reference value. When the magnetic tape (2) is raised, the reel-side motor that winds the magnetic tape (2) and the reel-side motor that unwinds the magnetic tape are activated based on a control signal that instructs to weaken the tension of the magnetic tape (2). In a magnetic tape device equipped with a tension servo circuit that controls the driving force so that the tension of the magnetic tape (2) is constant, when the air lifter function is operated, the magnetic tape is heated from above the magnetic head (1). From the floating magnetic tape (2) with a certain tension,
The amplitude of the analog signal read by the magnetic head (1) is
If the predetermined upper limit or lower limit is exceeded, an instruction means (1) instructs the air supply section (7) to adjust the air pressure.
7), and when the amplitude of the analog signal becomes larger than the upper limit value,
The air supply unit (7) is instructed to increase the air pressure, and when the amplitude of the analog signal becomes smaller than the lower limit value, the air supply unit (7) is instructed to decrease the air pressure. and controlling the amplitude of the analog signal to be between the upper limit value and the lower limit value while the air lifter function is in operation.