JP2001067601A - Magnetic tape device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the rewriting of the recording on a magnetic tape with the recording density of original data or the recording density different therefrom. SOLUTION: A history information storage part 22 is provided in a system control part 20 of a magnetic tape device 1 for storing the recording frequency and magnetic tape transporting speed applicable to this device and also a writing current value or erase current value in accordance with the specification of a magnetic tape medium and the recording density. After the history information being recorded on the history information section of the magnetic tape medium is read out, the overwriting or rewriting after erase is carried out at the time when the data are rewritten with the desired recording density.

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 that rewrites a recording on a magnetic tape at an original recording density or a recording density different from the original recording density.

[0002]

2. Description of the Related Art A magnetic tape device is an indispensable device for storing various data and backing up various information processing devices because a large amount of data can be recorded and accumulated at low cost. In this magnetic tape device, the track density and the recording density have been increased to improve the recording capacity of the magnetic tape. With the increase in density, it is also important to use existing huge data without any trouble.

[0003] Taking the recording frequency as an example, a rewriting method is disclosed as follows. If the recording frequency for recording data is increased, the storage capacity of the magnetic tape is increased, so that the recording frequency of the new device is usually higher than the recording frequency of the old device. If the recording frequency is low, the magnetic tape is magnetized to a deeper position in the thickness direction of the magnetic tape. Therefore, when rewriting recorded data by overwriting at a higher recording frequency, the recorded data may remain without being completely rewritten. Therefore, for example, in the technique disclosed in Japanese Patent Application Laid-Open No. 3-73401, it is determined whether or not the recording frequency for writing data on the magnetic tape is lower than the recording frequency of the device based on the management information on the magnetic tape. Judge,
When rewriting the data, there is disclosed an invention in which writing is performed after erasing the original data. By this processing, a decrease in S / N due to residual magnetism when recording at a low recording frequency is overwritten at a high recording frequency is avoided.

[0004]

In the above example, it is considered that a magnetic tape recorded by an old device is used by a new device having an improved recording frequency, but it is once rewritten at a high recording frequency. Conversely, the old data cannot be read by the old device. As described above, data compatibility is not always perfect with the improvement of device performance.

[0005] Since this compatibility is not perfect, it is necessary to manage whether or not each magnetic tape has been rewritten by a new device.
If there is a part rewritten by the new device, it is necessary to avoid using the old device or to replace all the magnetic tape devices used by the new device in order to avoid complicated management.

According to the present invention, there is provided a magnetic recording apparatus having a structure capable of selecting rewriting at the same recording density as already recorded data or at a different recording density in order to improve data compatibility between magnetic tape devices. It is an object to provide a tape device.

[0007]

The present invention focuses on the fact that the recording density of a magnetic tape is determined by both the recording frequency of a magnetic tape device and the running speed of the tape, and records the same recording density as the recorded data. The combination is selected from the combination of the frequency and the tape running speed, and the data recorded in this combination is rewritten. Further, at the time of rewriting, whether to overwrite directly or to record after AC erasing, in which a high-frequency current is applied to a magnetic head before recording to erase the magnetization of the magnetic tape, is determined based on data stored in advance, and once determined. AC that requires processing time for erasure
Recording after erasure was configured so that it could be kept to the minimum necessary.

More specifically, according to the first aspect of the present invention, a combination of magnetic tape transport speed information and write frequency information that can be executed by a magnetic tape device is stored in a storage unit. Based on the combination of the tape transport speed information and the write frequency information stored in the storage unit, when writing data to the position, the determination unit determines a combination of a magnetic tape transport speed and a write frequency at which overwriting is possible. The gist of the present invention is to provide a magnetic tape device characterized in that data is written to a designated position on a magnetic tape in any of these overwriteable combinations.

According to a second aspect of the present invention, in the magnetic tape device according to the second aspect, the determination section includes recording density information of a position of the magnetic tape to which writing is instructed and the magnetic recording information stored in the storage section. From the combination of the tape transport speed and the writing frequency, when writing data to the position, the determination unit determines in advance whether erasing is necessary, and when erasing is necessary, erases the magnetic field at the position where the writing is instructed. The gist of the magnetic tape device is characterized in that data is written to a designated position on the magnetic tape after the application.

According to a third aspect of the present invention, in the magnetic tape device according to the first or second aspect, the recording density information recorded at a predetermined position on the magnetic tape is read. Was the gist.

According to a fourth aspect of the present invention, there is provided the magnetic tape device according to the second aspect, wherein a position error between the magnetic tape and the magnetic head causes a position shift between the erasing magnetic field and the track. The gist of the present invention is to provide a magnetic tape device that applies an erasing magnetic field in a range that covers the vertical direction of a track so that magnetism does not occur.

According to a fifth aspect of the present invention, in the magnetic tape device according to the second aspect, when the erasing magnetic field is applied to the magnetic tape, the gap between the magnetic head and the magnetic tape is made larger than the gap at the time of recording or reproduction. The gist of the present invention is to provide a magnetic tape device configured so that an erasing magnetic field can be applied to a range covering a predetermined track.

According to a sixth aspect of the present invention, in the magnetic tape device according to the second aspect, the erasing process is performed by selecting a frequency and a current value of an output signal of the erasing circuit based on recording density information. The gist of the magnetic tape device is as follows.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a magnetic tape loaded on a reel, FIG. 2 is a diagram showing a state of transport of a magnetic tape medium, and FIG. 3 is a diagram showing a first embodiment according to the present invention, showing an entire configuration of a magnetic tape device. FIG. 4 is a diagram showing a flow of an operation of overwriting data on a magnetic tape, and FIG. 5 is a diagram showing a magnetic tape transport speed, recording frequency,
FIG. 6 is a diagram showing an example of write condition data such as a write current value, FIG. 6 is a diagram showing details of a write operation of the magnetic tape device, FIG. 7 is a diagram showing a change in a signal of the write operation, and FIG. FIG. 9 shows details of a drive circuit capable of selecting a write current value in an example.
FIG. 10 is a diagram showing a change in a signal at the time of AC erasing (referred to as AC erasing), and FIG. 10 is a diagram showing details of the read data generating unit.

First, the outline of the operation and functions of the present apparatus will be described with reference to FIGS. 1, 2 and 3. In FIG. 1, the magnetic tape 1
Reference numeral 00 denotes a magnetic tape medium 101, a resin reel 102 around which the tape main body is wound, a magnetic cartridge 103 for housing the reel 102, and a magnetic tape medium 101.
And a leader block 104 provided at the front end of the device. The leader block 104 is a member having a role of guiding the magnetic tape medium 101 along a predetermined transport path when the magnetic tape 100 is loaded in a magnetic tape device.
In the magnetic tape medium 101 near this block, a history information section 105 is provided. In this embodiment, information in the block is recorded in this section in correspondence with the model number of the magnetic tape and the block on the magnetic tape. History information such as a recording frequency and a tape speed at the time of recording is recorded.

Next, with reference to FIGS. 2 and 3, the state of transport of the magnetic tape 100 in the magnetic tape device will be described. When the magnetic tape 100 is loaded in the magnetic tape device, the leader block 104 shown in FIG. 1 reaches a take-up reel 110 via a predetermined transport route including a plurality of guide rollers 111, and the take-up reel 110
And a fitting portion provided on a rotating shaft portion (not shown). The take-up reel 110 and the reel 102 are each rotationally driven by a reel motor 11 for driving a reel and a cartridge reel motor 12 (each shown in FIG. 3). The transport amount is calculated based on the output signals of the tachogenerators 13 and 14 (each shown in FIG. 3) connected to each of the reel motors 11 and 12, and the magnetic tape medium 101 is calculated.
Is transported by a predetermined length. The transport route includes a read head 41, a write head 61 (see FIG. 3 for each),
Roller 11 for applying tension to magnetic tape medium 101
8 and the like, and in this embodiment, the magnetic tape 100
Simultaneously with the loading, the history information recorded in the history information section 105 already described is read by the read head 41 and stored in the history information storage section 22 in the system control section 20 (see FIG. 3).

Next, referring to FIG.
Will be described. The magnetic tape device 1 is connected to a host device not shown in FIG. 3, for example, a large computer, a workstation, a communication control device, a small computer, a personal computer, and the like via a cable 91.
The main commands from this higher-level device are a command for writing data on the magnetic tape medium 101 and a command for reading data recorded on the magnetic tape medium, which are transmitted to the interface unit 90 via the cable 91. Will be.

Since the feature of the present invention relates to rewriting of data recorded on a magnetic tape medium, the operation of the magnetic tape device 1 relating to the above read command will be described only briefly.

[Reading Operation] Upon receiving a reading command from the host device, the system control unit 20 transmits this command via the buffer memory 29 to the microprocessor 2.
5 (hereinafter, referred to as MPU). The MPU 25 analyzes the read command and sends the head position data of the data to be read to the tape drive control unit 30. The tape drive control unit 30 drives the reel motor 11 and the cartridge reel motor 12 via the tape drive unit 10 based on the head position data, and outputs signals from the tacho generators 13 and 14 directly connected to the respective motors. Based on
The magnetic tape medium 101 is wound by a predetermined amount. afterwards,
The MPU 25 issues a read start command to the tape drive control unit 3
0, the tape drive control unit 30 drives the reel motor 11 and the cartridge reel motor 12 via the tape drive unit 10, and sends a gain selection signal of a read amplifier to the read data generation unit 40 to send the read amplifier. Set the gain and start reading. Read head 4
The data read in 1 is subjected to signal processing such as band pass and peak pulse detection in a read data generation unit 40, and is converted into a pulse signal.
"0", "0" at the peak pulse-to-digital converter 28
After that, the data is converted into a digital signal of "1". The data is subjected to error correction processing by the data correction unit 24, and is transmitted to the cable 91 via the MPU 25, the buffer memory 29, and the interface unit 90.

Next, an operation of the magnetic tape device 1 based on a write command including a rewrite operation, which is a feature of the present invention, will be described with reference to FIGS. [Write Operation] When the magnetic tape 100 is loaded and the data of the history information section 105 (see FIG. 1) is stored in the history information storage section 22, the magnetic tape device 1 enters the start state of the write operation (FIG. Step 200 of FIG. 4 and the following steps refer to the steps in FIG. 4).

A write command from the host device includes write position information and data to be written. When this write command is received by the system control unit 20 via the cable 91 and the interface unit 90 (step 20).
1), the MPU 25 reads the history information of the position indicated by the writing position information from the history information storage unit 22 (step 202). The history information includes the model of the magnetic tape 100 and the recording density of the writing position, and the writing condition data corresponding to the model and the recording density is read from the writing condition storage unit 21. An example of the write condition data is shown in FIG. 5 (details will be described later).

Next, the recording density for recording new data is the same as the recording density before rewriting, or a new recording density is set from the keyboard 23 in FIG. 3 (step 203) and input to the MPU 25. You.

Next, the MPU 25 determines whether rewriting is to be performed by overwriting or recording is to be performed after erasing data at that location (step 204). This determination is performed using the write condition data read from the write condition storage unit 21. The write condition data (see FIG. 5) includes combinations of the recording frequency F and the tape speed V that can be implemented in the magnetic tape device 1, and stores as many tables as the number of combinations of the tape type and the recording density. ing. Further, the write current value Wa for overwriting is stored in association with each combination of F and V that determines the recording density ρ (ρ = F / V) set in step 203. This Wa
It is preferable to use a current value obtained by an experiment in advance. The combination of F and V in which the value of Wa is not described indicates that overwriting is not preferable because the original data remains in writing by overwriting and causes noise.
In FIG. 5, F and V do not show specific values, but it is preferable to design them so as to cover the recording density of other models. If the tape speed V is taken as an example, it is not always necessary to set the speed in increments of 0.5 as shown in FIG. 5, but may be set more finely.

If the recording density of rewriting is 1.5 ρ, it can be executed if the recording frequency is set to 1.5 F, the tape speed is set to V, and the write current is set to I ₃₂ , and it is determined that overwriting is possible. (Step 204). On the other hand, if the recording density is set to 3ρ in order to perform recording at a higher density, the data of the write current value is not specified, so that the data before rewriting cannot be erased by overwriting, and the erasing process is performed once. It is determined that writing needs to be performed later (step 204).

When it is determined that overwriting is possible, the magnetic tape device 1 performs a writing operation. This write operation will be described with reference to FIGS. The MPU 25 instructs the tape drive controller 30 to write / read position information and write condition information (information indicating the tape speed and write current among the recording frequency, tape speed, and write current value obtained from the write condition data). And send. The tape drive control unit 30 drives the reel motor 11 and the cartridge reel motor 12 via the tape drive unit 10 based on the write / read position information, respectively.
The magnetic tape medium 101 is moved near the write start position of the magnetic tape medium 101 to the position of the write head 61, and the angular velocities of both motors are controlled in accordance with the tape speed information included in the write condition information so that the magnetic tape medium 101 is moved at a predetermined tape speed. Is transported. On the other hand, the data generation unit 70 of the write data generation unit 60
The MPU 25 sends a write enable signal (see FIG. 7) indicating a writable period, and the clock generator 26
(Machine clock 1, see FIG. 7). Further, the write data stored in the buffer memory 29 ("" in FIG. 7)
0 ”and“ 1 ”correspond to the external data).
, The peak of which is the TTL level NRZI write data (corresponding to the NRZI signal in FIG.
ZI is Non-Return-to-Zero Inv
, and sent to the data generation unit 70. This NRZI write data is DDNRZI signal write data (DDNRZI is Double-Densi) having peaks on both the plus and minus sides in the data generation unit 70.
ty-Non-Return-to-Zero-Inv
erse), and sent to the drive unit 71. The drive unit 71 converts the peak current value of the DDNRZI write data into a current value Wa (write current value) selected by the write condition data based on a write current selection signal from the tape drive control unit 30 ( DDNRZ of FIG.
I signal).

DDNR whose peak current value is ± Wa
The ZI write data is applied to the write head 61 (Step 205). A magnetic field based on the applied current is applied to the magnetic tape medium 101, and the magnetic tape medium 101 is magnetized. The waveform read from the magnetized magnetic tape medium 101 is the magnetic tape read waveform shown in FIG. 7, and a read waveform corresponding to data "1" is obtained.

An example of converting the NRZI signal into a DDNRZI signal will be described with reference to FIG. In FIG. 7, the data string "
100010001 "is correspondingly converted to a TTL level NRZI signal and a DDNRZI signal indicated by a current waveform. In the data sequence, the NRZI signal is inverted with respect to" 1 ". Then, follow the rules below.

Inversion when "1". (Position of arrow a) When "0", it is reversed at the middle (location of arrow c) from the beginning (location of arrow b).

No inversion occurs at "0" before "1".
The current value Wa is selected by the drive unit 71 by a current selection signal from the tape drive control unit 30. As a specific example of the current value selection, FIG. 3 shows a selection circuit.

In FIG. 8, current selection signals from the tape drive control unit 30 are indicated by A and B. A and B are "0", "
With the combination of this input with the signal of "1", "L" (low level) and "H" of the outputs Y1 and Y2 of the selector.
(High level) combination is selected.
The transistors TR1 and TR2 are of NPN type, and when an “H” signal (high level signal) is input to each base,
Conduction occurs between the emitter and the collector. The transistors TR3 to TR6 are of the PNP type, and when an "L" signal (low level signal) is input to each base, conduction between the emitter and the collector is made. ON / O between the emitter and collector of TR3 to TR6 depending on the combination of Y1 and Y2
The combination of the resistors R1 to R6 which are set as the FFs and serve as the limiting resistors is determined, and the current value flowing through the write head 61 is selected. On the other hand, the write enable signal NO
ON / OFF of TR1 and TR2 is determined by an AND condition between the output of the T circuit and the output of the latch circuit of the DDNZRI signal,
The direction of the current flowing through the write head 61 is set.

On the other hand, if it is determined in step 204 that the writing is to be performed after the erasing process, the erasing process is performed in step 206. This erasing process is performed on the magnetic tape medium 10.
A magnetic field for erasing is applied in advance to 1 to reduce the already recorded magnetization on the tape medium to an acceptable level. In this embodiment, an AC erasing method (hereinafter, referred to as AC erasing) in which an alternating current is applied to the write head 61 and an alternating magnetic field having an alternating magnetic field direction is applied to the magnetic tape medium 101 is employed in this embodiment. This method has an advantage that the write head 61 can be used as an erasing magnetic head. As another method, a DC erasing method in which a magnetic tape medium is magnetized in a fixed direction or a magnet erasing method in which the magnetisms of a plurality of permanent magnets are alternately arranged can be adopted.

In the AC erasing used in this embodiment, an alternating current is applied to the write head 61, so it is necessary to select erasing conditions including the frequency of the applied current, the applied current value, and the tape speed. This condition is registered in advance in the write condition data (see FIG. 5) stored in the write condition storage unit 21. In other words, when writing is performed at a tape speed of 0.5 V and a recording frequency of 1.5 F at a location recorded on a magnetic tape of tape type XXXX at a recording density of YYYY, an alternating current of ± Wb at a frequency of 1.5 F is applied. This shows that if the voltage is applied to the write head 61, the already recorded data can be sufficiently demagnetized. In other words, the tape speed is 0.5V
In the case of, when an alternating current having a frequency of 1.5 F and a current peak value of ± Wb is applied to the write head 61, data already recorded at a recording density of YYYY on the magnetic tape of the tape type XXXX is sufficiently demagnetized. The necessary erasing magnetic field is obtained.

The erase condition (frequency of applied current, current value for erase, tape speed) obtained from the write condition data
Then, as in the case of the write operation, write / read position information indicating the erase start position is sent from the system control unit 20 to the tape drive control unit 30 (see FIG. 6). The tape drive control unit 30 controls the tape drive unit 10 as in the case of the write operation. On the other hand, the tape drive control unit 30 sends an erase frequency selection signal based on the applied current frequency of the erase condition to the data generation unit 70 in order to select the AC frequency applied to the write head 61 (see FIG. 6). Further, the tape drive control unit 30 sends a current selection signal based on the erase current value of the erase condition to the drive unit 71 (see FIG. 6).

On the other hand, from the system control unit 20 to the write data generation unit 60, the machine clock MCLK,
A write enable signal for defining the erase timing is sent (see FIG. 6).

Next, generation of an AC erase current having a predetermined frequency and current value will be described with reference to FIG. The reel drive 11 and the cartridge reel motor 12 are rotated by the tape drive unit 10 under the control of the tape drive control unit 30. With this rotation, the tacho generators 13, 14
, A tacho generation pulse is generated, and the tape drive unit 10,
The data is sent to the system control unit 20 via the tape drive control unit 30. A predetermined time is measured from the start of the tacho generation pulse based on the MCLK signal, that is, when the position of the magnetic tape medium 101 to be erased reaches the position of the write head 61, the write enable signal rises.

When the write enable signal goes high, the clock generation unit 7 of the data generation unit 70 receives the erase frequency selection signal sent from the tape drive control unit 30.
2 of the plurality of clocks generated in step 2
CLK2 is selected, and based on this clock signal,
A TTL level DDNRZI signal is generated. This D
The DNRZI signal is sent to the drive unit 71 and becomes a DDNRZI signal (current waveform) having a peak current value of ± Wb (current value) selected by the current selection signal. This current waveform DDNRZI signal is applied to the write head 61,
As shown in "direction of applied magnetic field" in FIG. 9, an alternating magnetic field having a predetermined frequency in the direction is applied to magnetic tape medium 101, and the magnetization of magnetic tape medium 101 is demagnetized.

The alternating magnetic field is applied to the magnetic tape medium 101 while the write enable signal is HIGH. When a predetermined number of tacho generation pulses are counted,
That is, when the magnetic tape medium 101 is conveyed within the range to be erased, the MPU 25 of the system control unit 20 changes the write enable signal to LOW, and the application of the erasing magnetic field to the magnetic tape medium 101 ends (step 206). When the erasing magnetic field is applied, the magnetic tape medium 101 is read by the read head 41 provided close to the write head 61 to confirm that the residual magnetization is below a specified level. The signal read by the read head 41 is sent to the read data generation unit 40.

Since the read signal after demagnetization after the AC erasure is smaller than the signal from which data is read, the present embodiment employs the configuration shown in FIG.
In addition to the preamplifier 42 used for normal data reading, the signal is amplified by two stages of the noise detection amplifier 43, and the switches 44 and 45 are used to amplify the signal of the preamplifier 42 alone or the preamplifier 42 and the noise detection amplifier 43. It is configured to be able to select the amplification of the stage. With this configuration, the preamplifier 42 is controlled by a gain selection signal from the tape drive control unit 30.
Sets the switch 45 to the conductive state and sets the switch 44 to the open state by the noise detection selection signal from the tape drive control unit 30 to a maximum gain, and amplifies the read signal after the AC erasure.

The signals amplified by the two-stage amplifiers 42 and 43 are subjected to signal processing by an equalizer 46 including a band-pass filter and a peak pulse detection circuit. In this peak pulse detection circuit, for example, the slice level is set to ± 300 mV
It is determined whether the S / N ratio of the noise level is equal to or less than a predetermined value based on the presence or absence of a signal exceeding this range. If the signal exceeds this slice level, a peak pulse is generated, and data "1" is generated in the peak pulse-to-digital converter 28 (see FIG. 3) of the system controller 20, and based on this data "1". In MPU25, A
After C erasure, it is determined that the residual magnetization is not below a predetermined level. In this case, a larger erasing current is selected by the current selection signal, and if it is determined that there is residual magnetization even at the maximum current value, AC erasing is performed with a lower erasing frequency and a lower tape speed (step 208). .

If data "1" does not appear in the output of the peak pulse-to-digital converter 28, it is determined that the AC erasure has been completed, and the flow proceeds to the writing operation in step 209. Regarding the above noise level, if the signal (data “1”) is not detected when the gain of the noise detection amplifier 43 is set to 30 dB and the slice level is set to ± 300 mV,
Noise is 9 mV or less at the output side of the preamplifier 42 (S / N
The ratio is 30 dB or more). If S / N
If it is necessary to further increase the ratio, a high-gain noise detection amplifier may be used.

Thereafter, the magnetic tape medium 101 is rewound, and write data is written to the magnetic tape medium 101 by the above-described writing operation (step 209). At the same time as writing in step 205 or step 209, the read head 41 arranged close to the write head 61
Thus, the written data is read (step 210). The purpose of this reading is to verify whether the write data has been correctly written.

The read signal is sent to the preamplifier 42 of the read data generator 40 (see FIG. 10). The gain of the preamplifier 42 is
From the gain selection signal, for example, 100 times, 150 times
You can select from different gains such as double, 200 times, and 300 times. The gain determined by the recording density is selected by the gain selection signal.

The read signal amplified by the preamplifier 42 normally passes through a switch 44 and is supplied to an equalizer 46 including a band-pass filter and a peak pulse detection circuit.
The signal is converted into a pulse train by signal processing, and then sent to a peak pulse-to-digital converter 28 (see FIG. 3) of the system controller 20.

The read signal is converted into a digital signal and then input to the MPU 25 to be input to the buffer memory 2.
The error rate is calculated by comparing with the write data in step 9 (step 211). If this error rate is larger than a predetermined value,
The write current is increased via the current selection signal, and the write operation is terminated when the error rate falls below a predetermined value (step 21).
2).

In the first embodiment, since the storage unit for storing the recording conditions is provided in the magnetic tape device, the history information of the loaded magnetic tape is read, and the recording density is obtained from the history information. This makes it possible to rewrite the magnetic tape under recording conditions corresponding to the recording density, and to rewrite the magnetic tape at another recording density by selecting another combination of recording frequency and tape speed.

Furthermore, if overwriting is possible in accordance with the already recorded recording density, overwriting is performed based on the writing condition data in which the writing current value data is made to correspond to the combination of the recording frequency and the tape speed. Made it possible.

Further, if the overwriting is not possible, the current applied to the magnetic head which generates an alternating magnetic field before writing data is determined by the combination of the recording frequency and the tape speed if overwriting is not possible, in accordance with the already recorded recording density. Corresponding values, A
C erasure was enabled.

Furthermore, since the combination of the overwriteable recording frequency and the tape speed and the combination of the recording frequency and the tape speed requiring AC erasing are stored in correspondence with the already recorded recording density, the erasing is performed. It is possible to overwrite without using AC erasure requiring extra time, and it is possible to select a combination of a rewritable recording frequency and a tape speed with the highest recording density.

Next, a second embodiment of the present invention will be described. The second embodiment relates to a configuration for reliably applying a magnetic field for erasure to a recording track to be erased. The key point for reliably applying this magnetic field to the recording track is to move the magnetic head that generates the erasing magnetic field in a direction perpendicular to the running direction of the recording track, that is, in the width direction of the magnetic tape medium, so that the magnetic tape can be transported. The configuration is such that even if the deviation occurs, it can be reliably applied to the recording track. The second embodiment will be described below with reference to FIG. A magnetic head 300 shown in FIG. 11 is a magnetic head capable of recording / reading a multi-track on a magnetic tape medium, in which a write head 310 and a read head 320 are integrated. On the write head 310 side, a plurality of shields 312 and cores 311 are arranged in the width direction of the magnetic tape medium. The shield 312 is provided to prevent magnetic interference between the cores 311. The gap 313 is a gap for generating a magnetic field applied from the core 311 to the magnetic tape medium. The coil wound around the core 311 and a connector for connecting the coil to an external circuit are not shown. The shield 322, the core 321 and the gap 323 are similarly arranged on the read head 320 side. A shield 330 is provided between the write head 310 and the read head 320 to prevent magnetic interference between the write head 310 and the read head 320.
Is provided. The surface of the magnetic head 300 of the present embodiment in contact with the magnetic tape medium, that is, the surface on which the cores 311 and 321 are arranged is a convex surface, but is constituted by a flat surface or a convex surface on which a row of cores 311 and a row of cores 321 are arranged. May be.

The rotor W is provided on the side of the magnetic head 300.
341 and the rotor R343 are fixed. The stator W340 is located at a position facing the rotors 341 and 343.
Stator R342 is arranged. Here, although not shown, the magnetic head 300 includes the two stators 340 and 34.
The base 2 is supported by an elastic support member such as a leaf spring or a coil spring so as to be movable in the width direction of the magnetic tape. This stator 34
The coils 0 and 342 and the rotors 341 and 343 are electromagnets, and are configured to generate a force for moving the magnetic head 300 in the width direction of the magnetic tape when energizing each coil. FIG. 12 shows a cross section in the DD direction of the drawing, and a detailed structure of the stator and the rotor will be described.

FIG. 12 is a sectional view showing a cross section of the stator R342 and the rotor R343, which are arranged with a gap therebetween. The stator R342 includes a core 344 and two coils 345 and 346, and the rotor R343 includes a core 347 and two coils 348 and 349. Core 3
44, 347 are high permeability materials, for example, electromagnetic soft iron, silicon steel,
Or it is made from Permalloy. Coil 34
5, 346, 348, and 349 can be individually energized, and when only the coils 346 and 349 are energized and the direction of the current applied to the coils 346 and 349 is selected so that the loop A becomes a magnetic flux loop, the opposing surfaces The rotor 343 moves so that C and B are almost aligned, that is, the magnetic head 300 moves downward in the illustrated arrow direction and stops at a position where the surfaces B and C are almost aligned. Similarly, by energizing the coils 345 and 348, it becomes possible to move the magnetic head 300 upward with the arrow. In the present embodiment, the amount of movement of the magnetic head 300 in the upward and downward directions is determined by the position where the opposing surfaces B and C of the core coincide with each other, but all of the coils 345, 346, 348 and 349 are energized. Coil 345 and coil 346
The magnetic head 300 may be configured to move the magnetic head 300 to an arbitrary position within the upper and lower δ by controlling the respective current values of the magnetic head 300.

When an erasing magnetic field is applied to the magnetic tape while the magnetic head is moved in the width direction of the magnetic tape by the magnetic head having the stator and the rotor as described above, the magnetic head moves upward or downward beyond the recording track width. An erasing magnetic field can be applied. For more complete erasing, it is desirable to move the magnetic head upward and erase it, and then rewind the magnetic tape or after rewinding and transport it again to move the magnetic head downward and erase.

In the second embodiment, when the erasing magnetic field is applied to the magnetic tape, the position of the magnetic head can be moved in the width direction of the recording track of the magnetic tape, so that the erasing magnetic field is applied beyond the track width. Therefore, even if the running of the magnetic tape is shifted between recording and erasing, the recorded data remains unerased, that is, erasure can be performed without residual magnetization.

Next, a third embodiment will be described. The third embodiment, like the second embodiment, is an embodiment for performing erasing more completely. In the second embodiment, the erasing magnetic field is applied after the magnetic head is moved in response to the positional deviation of the recording track. The third embodiment will be described with reference to FIG.

The magnetic tape medium 101 is provided with tension arms 112 and 113 in the tape traveling path so as to be in close contact with the read head 41 and the write head 61 of the magnetic head. At one end of each tension arm,
A solenoid 114 for generating a force applied to the magnetic tape medium 101 and a tension spring 116 for generating a force in a direction opposite to a suction direction of the solenoid are provided.

This embodiment is characterized in that the solenoid 114
By setting the suction force of the magnetic tape medium weak at the time of erasing, the gap between the magnetic tape medium 101 and the write head 61 is widened. As the distance from the core portion, which is the magnetic field generating portion of the write head 61, increases, the distribution of the magnetic field becomes wider. Therefore, when the gap is wide, when the erasing magnetic field is applied, the erasing magnetic field is applied to a wide range of the recording track. Become. Therefore, even if the travel of the magnetic tape medium 101 shifts and the write head position deviates from the recording track, the erasing magnetic field can be applied to the track, and the residual magnetization can be reduced.

The effect of the third embodiment is, in addition to the effect of the second embodiment, that an erasing magnetic field can be simultaneously applied in the vertical direction of the recording track width, and the magnetic tape can be run only once. This has the effect of enabling erasure.

[0058]

According to the first aspect of the present invention, since the combination of the magnetic tape transport speed and the write frequency at which the predetermined position of the loaded magnetic tape can be rewritten by overwriting can be selected, the original recording density can be maintained. Or, overwriting and rewriting at different recording densities become possible, which has the effect of expanding the compatibility of the magnetic tape.

According to the second aspect of the present invention, it is possible to determine in advance whether a predetermined position of the loaded magnetic tape is overwritten or rewritten after erasing, and it is possible to rewrite at the original recording density or at a different recording density. This has the effect of expanding the compatibility of the magnetic tape.

According to the third aspect of the present invention, since the recording density information recorded at a predetermined position on the magnetic tape is read, the effect of the first or second aspect can be obtained according to the loaded magnetic tape. Has.

According to the fourth to sixth aspects of the present invention, residual magnetism based on data already recorded on the magnetic tape can be reduced.

[Brief description of the drawings]

FIG. 1 is a view showing a magnetic tape.

FIG. 2 is a diagram showing a state of transport of a magnetic tape.

FIG. 3 is a diagram showing a first embodiment.

FIG. 4 is a diagram showing a flow of an overwriting operation.

FIG. 5 is a diagram showing write condition data.

FIG. 6 is a diagram showing details of a write operation.

FIG. 7 is a diagram showing a change in a signal at the time of writing.

FIG. 8 is a diagram showing details of a write drive circuit.

FIG. 9 is a diagram showing an operation of AC erasing.

FIG. 10 is a diagram showing details of a read data generation unit.

FIG. 11 is a view showing the appearance of a magnetic head.

FIG. 12 is a diagram showing details of a rotor and a stator.

[Explanation of symbols]

 Reference Signs List 20 system control unit 21 writing condition storage unit 22 history information storage unit 30 tape drive control unit 40 read data generation unit 41 read head 60 write data generation unit 61 write head 101 magnetic tape medium

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shoji Tosa 35th, Saho, Kato-gun, Hyogo (No address) Inside Fujitsu Peripheral Machinery Co., Ltd. (72) Inventor Hiroyuki Miyata 35th, Saho, Kato-gun, Hyogo ( (No address) Inside Fujitsu Peripheral Machinery Co., Ltd. (72) Inventor Daina Konishi 35, Saho, Kato-gun, Hyogo Prefecture (No address) Inside Fujitsu Peripheral Machinery Co., Ltd. (72) Inventor Tatsuya Yumoka, Saho, Kato-gun, Hyogo Prefecture No. 35 (No address) Inside Fujitsu Peripheral Machinery Co., Ltd. (72) Inventor Takanobu Kashiwagi Saho, Kato-gun, Hyogo Prefecture No. 35 (No address) Inside Fujitsu Peripheral Machinery Co., Ltd. (72) Inventor Yukio Sekiguchi Kato-gun, Hyogo Prefecture Machi Saho No. 35 (No address) Fujitsu Peripheral Machinery Co., Ltd. F-term (reference) 5D031 AA01 EE07 EE08 HH01 5D091 AA01 CC30 HH20

Claims (6)

[Claims] 1. A magnetic tape device on which a magnetic tape can be mounted, a storage unit storing a combination of magnetic tape transport speed information and write frequency information, recording density information at a position on the magnetic tape where writing is instructed, and A determination unit that determines a combination of a magnetic tape transport speed and a write frequency that can be overwritten when writing data to the position based on a combination of the magnetic tape transport speed information and the write frequency information stored in a storage unit; A magnetic tape device, wherein data is written to a designated position on the magnetic tape in any of the overwritable combinations determined by the determination unit. 2. A magnetic tape device capable of mounting a magnetic tape, comprising: a storage unit storing a combination of magnetic tape transport speed information and write frequency information; and a magnetic head for generating an erasing magnetic field applied to the magnetic tape. An erasing circuit, when writing data at the position based on the recording density information indicating the recording density of the information recorded at the position of the magnetic tape to which the writing is instructed and the combination stored in the storage unit. Having a determining unit for determining whether or not erasing is necessary in advance, upon writing to the position on the magnetic tape, activating the erasing circuit when the determining unit determines that erasing is necessary A magnetic tape device, wherein an erasing magnetic field is applied to the magnetic head at the position. 3. The magnetic tape device according to claim 1, wherein the recording density information recorded at a predetermined position on the magnetic tape is read. 4. The magnetic tape device according to claim 2, wherein the erasing magnetic field is applied to a range covering a vertical direction of a track of the magnetic tape to be erased. 5. The magnetic tape device according to claim 2, wherein when applying the erasing magnetic field to the magnetic tape, a gap between the magnetic head and the magnetic tape is made larger than a gap at the time of recording or reproduction. A magnetic tape device for applying the erasing magnetic field. 6. The magnetic tape device according to claim 2, wherein the erasing process is performed by selecting a frequency and a current value of an output signal of the erasing circuit based on recording density information. .