JP2007250111A - DC degaussing head, servo writer, and magnetic tape manufacturing method - Google Patents

Abstract

Disclosed is a DC degaussing head capable of preventing damage to a magnetic tape by preventing sliding between the magnetic pole and the magnetic tape, and recording signals and data on the magnetic tape in a good recording state. Let it be an issue.
A DC demagnetizing head 20 includes an N pole (first magnetic pole) and an S pole (second magnetic pole) respectively disposed on both sides of a magnetic tape MT. The magnetic tape MT is characterized by being spaced apart in the forward direction (longitudinal direction).
[Selection] Figure 3

Description

  The present invention relates to a DC degaussing head for magnetizing a magnetic tape in one longitudinal direction, a servo writer using the DC degaussing head, and a magnetic tape manufacturing method using the servo writer.

  In recent years, high-density recording of magnetic tapes has progressed, and some of them have a storage capacity of about 400 gigabytes for computer backup. Therefore, several hundred data tracks are formed on the magnetic tape in the width direction. Therefore, the width of the data track is very narrow, and the space between adjacent data tracks is also very narrow. Therefore, in order to trace the recording / reproducing element of the magnetic head to the data track, a servo signal is written in advance on the magnetic tape, and this servo signal is read by the magnetic head to thereby determine the position of the magnetic head (in the width direction of the magnetic tape). Servo position).

  Here, in the magnetic tape recording / reproducing apparatus, the change point of magnetization in the servo signal is detected by the change of electric resistance by the servo signal reading element (MR element), and the change point of magnetization as the read signal is differentiated waveform (voltage value). ). Therefore, as the change in the electrical resistance of the MR element increases, the peak voltage value of the read signal of the servo signal increases and the SN ratio of the read signal improves.

  However, in the future, when the recording density of magnetic tape is increased to several tens of terabytes, the number of data tracks on magnetic tape increases, the width of data tracks and the distance between adjacent data tracks become narrower, and The tape itself is also thinned. As a result, the amount of magnetism that can be detected when reading the servo signal decreases, the peak voltage value of the read signal of the servo signal decreases, and the SN ratio of the read signal deteriorates. As a result, the magnetic tape recording / reproducing apparatus cannot read the servo signal accurately and cannot control the position of the magnetic head.

  Therefore, as a method for improving the S / N ratio of the read signal of the servo signal, the servo band of the magnetic tape is magnetized in one direction toward one direction in the longitudinal direction of the magnetic tape (for example, the traveling direction of the magnetic tape). There is a method of writing a servo signal by magnetizing a servo band in a direction opposite to the one direction after DC erasure (hereinafter referred to as “DC demagnetization”). In this method, when the servo signal is read by the servo signal reading element of the magnetic head, the change rate of the magnetic field and the switching portion between the ground portion in one direction and the servo pattern magnetized in the reverse direction are changed. Since the amount of change increases, the output of the servo signal increases, and the SN ratio of the read signal of the servo signal can be improved (see, for example, Patent Document 1).

  Some DC degaussing heads (direct current erasing heads) for magnetizing the magnetic tape in one longitudinal direction use permanent magnets. In such a DC demagnetizing head, the magnetic tape is magnetized by causing a magnetic field directed in one direction in the longitudinal direction of the magnetic tape to act on the magnetic layer of the magnetic tape by bringing the magnetic pole of the permanent magnet closer to the traveling magnetic tape. (For example, refer patent document 2).

Japanese Patent Laying-Open No. 2004-318977 (paragraphs 0026 to 0027, FIG. 1) JP 2005-166230 A (paragraphs 0040-0041, FIG. 3) US Pat. No. 6,970,312 US Patent Application Publication No. 2005/0099718 US Patent Application Republished No. 2005/0105967 US Patent Application Publication No. 2005/0168869 US Patent Application Publication No. 2005/0219734

Here, as shown in FIG. 5, in the conventional DC degaussing head 120 using the permanent magnet 121, the permanent magnet 121 is disposed on one surface side of the magnetic tape MT. In order for the permanent magnet 121 to cause a magnetic field in the longitudinal direction to act on the magnetic tape MT, it is necessary to bring the N magnetism and the S pole of the permanent magnet 121 close to the surface of the magnetic tape MT. Therefore, when the magnetic tape MT is run, the permanent magnet 121 and the magnetic tape MT are easy to slide.
When the permanent magnet 121 and the magnetic tape MT slide and the recording layer of the magnetic tape MT is damaged, when the servo signal is written on the magnetic tape MT, the servo signal is dropped or rubbed. Since the magnetic tape MT powder adheres to the recording surface and a part of the servo signal is lost, there is a problem that the recording state of the magnetic tape MT is deteriorated.

  Therefore, in the present invention, when the magnetic tape is magnetized in one direction in the longitudinal direction, the magnetic pole can be prevented from sliding with the magnetic tape when the magnetic tape is magnetized in the longitudinal direction. It is an object of the present invention to provide a DC degaussing head and a servo writer that can record signals and data on a tape in a good recording state, and a method for manufacturing a magnetic tape.

  In order to solve the above-described problems, the present invention provides a DC demagnetizing head for magnetizing a magnetic tape in one longitudinal direction, and a first magnetic pole and a second magnetic pole respectively disposed on both sides of the magnetic tape. The first magnetic pole and the second magnetic pole are characterized by being spaced apart in the longitudinal direction of the magnetic tape.

  According to this configuration, the first magnetic pole and the second magnetic pole are respectively arranged on both sides of the magnetic tape, and the magnetic field generated between the first magnetic pole and the second magnetic pole is from one side of the magnetic tape. It will pass to the other side. At this time, since the first magnetic pole and the second magnetic pole are spaced apart in the longitudinal direction of the magnetic tape, the magnetic field passing through the magnetic tape acts obliquely with respect to the longitudinal direction of the magnetic tape. become. The magnetic tape is magnetized in one direction in the longitudinal direction by the longitudinal component of the magnetic tape in the magnetic field acting obliquely with respect to the magnetic tape. As a result, the magnetic tape can be magnetized in one direction in the longitudinal direction without bringing the magnetic pole close to the magnetic tape, so that sliding between the magnetic pole and the magnetic tape can be prevented, and damage to the magnetic tape can be prevented. it can.

  The first magnetic pole and the second magnetic pole can be constituted by, for example, an N pole and an S pole of a permanent magnet. Specifically, a configuration in which the magnetic tape is sandwiched between the north and south poles of an integral U-shaped permanent magnet, or permanent magnets are arranged on both sides of the magnetic tape, and the north or south pole of each permanent magnet is magnetized. There is a configuration that points to the tape. Furthermore, an electromagnet can also be used, and similarly to the case of a permanent magnet, the magnetic tape may be sandwiched between the N pole and S pole of an integral electromagnet, and the electromagnet may be disposed on both sides of the magnetic tape.

  The servo writer using the DC degaussing head described above is a servo writer used for manufacturing a magnetic tape in which servo signals for tracking control of the magnetic head are written in the servo band and data is recorded in the data band. A magnetic tape running system for winding and running the magnetic tape fed from the delivery reel with a take-up reel, and a DC demagnetizing head for magnetizing at least the servo band of the running magnetic tape in one direction in the longitudinal direction of the magnetic tape; A servo signal writing head which is arranged downstream of the DC demagnetizing head in the magnetic tape traveling direction, and magnetizes the servo band of the traveling magnetic tape in a direction opposite to one direction to write a servo signal; It is characterized by having.

  Furthermore, a method for manufacturing a magnetic tape using the servo writer described above, wherein the magnetic tape travels from the feed reel to the take-up reel by the magnetic tape travel system, and the magnetic tape travels by the DC demagnetizing head. Magnetizing at least the servo band in one direction in the longitudinal direction of the magnetic tape, and magnetizing the servo band in one direction opposite to the one direction by the servo signal writing head to write the servo signal. It is a feature.

In these configurations, after the magnetic tape is magnetized in one direction in the longitudinal direction, the servo band is magnetized in the opposite direction to the one direction and the servo signal is written, and when the servo signal is read by the magnetic head In addition, the rate of change and the amount of change in the magnetic field increase, and the output of the servo signal increases. As a result, the SN ratio of the read signal of the servo signal is improved, so that the position control of the magnetic head can be performed with high accuracy.
In the DC degaussing head, the first magnetic pole and the second magnetic pole respectively disposed on both sides of the magnetic tape are spaced apart in the longitudinal direction of the magnetic tape, and therefore pass through the magnetic tape. The magnetic field acts obliquely with respect to the longitudinal direction of the magnetic tape. Of the magnetic field applied to the magnetic tape, the magnetic tape is magnetized in one longitudinal direction by the longitudinal component of the magnetic tape. As a result, the magnetic tape can be magnetized in one direction in the longitudinal direction without bringing the magnetic pole close to the magnetic tape, so that sliding between the magnetic pole and the magnetic tape can be prevented, and damage to the magnetic tape can be prevented. it can. Therefore, the above-described servo writer and magnetic tape manufacturing method can manufacture a high-quality magnetic tape.

  According to the DC degaussing head of the present invention, the magnetic field passing through the magnetic tape acts obliquely with respect to the longitudinal direction of the magnetic tape. Is magnetized in one direction in the longitudinal direction. As a result, the magnetic tape can be magnetized in one direction in the longitudinal direction without bringing the magnetic pole close to the magnetic tape, so that sliding between the magnetic pole and the magnetic tape can be prevented, and damage to the magnetic tape can be prevented. it can. Therefore, signals and data can be recorded on the magnetic tape in a good recording state.

According to the servo writer and the magnetic tape manufacturing method of the present invention, the servo signal output is increased by magnetizing the magnetic tape in the direction opposite to the direction in which the magnetic tape is magnetized, thereby increasing the servo signal output signal. Therefore, the position of the magnetic head can be controlled with high accuracy.
Further, by using a DC degaussing head in which the first magnetic pole and the second magnetic pole respectively disposed on both sides of the magnetic tape are spaced apart in the longitudinal direction of the magnetic tape, high-quality magnetic Tapes can be manufactured.

Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
1A and 1B are diagrams showing a magnetic tape of the present embodiment, in which FIG. 1A is an enlarged plan view for explaining the magnetization state of the magnetic tape, FIG. 1B is a diagram showing a servo signal read from the magnetic tape, and FIG. ) Is a diagram showing signals when writing servo signals. FIG. 2 is a configuration diagram showing the servo writer of this embodiment. 3A and 3B are configuration diagrams showing the DC demagnetizing head of the present embodiment, in which FIG. 3A is a side view of an aspect in which the magnetic tape is magnetized, and FIG. 3B is a front view of an aspect in which the magnetic tape is magnetized. is there.

  First, after describing the configuration of the magnetic tape of the present embodiment, the configuration of a servo writer for writing a servo signal to the magnetic tape will be described, and further, a method of manufacturing a magnetic tape using the servo writer will be described.

[Configuration of magnetic tape]
As shown in FIG. 1A, the magnetic tape MT of the present embodiment has a plurality of servo bands SB extending in the longitudinal direction of the tape and a data band DB positioned between the servo bands SB. .

  Each servo band SB is magnetized in the traveling direction (see the arrow in the drawing. In the present embodiment, this traveling direction is appropriately referred to as “forward direction”), which is one direction in the longitudinal direction of the magnetic tape MT. . In FIG. 1, the magnetized direction is indicated by small arrows. The servo signal SS is written by magnetizing the servo band SB in the forward direction and the reverse direction.

The servo signal SS is a burst Ba that is magnetized in two stripes having a positive inclination angle with respect to the traveling direction of the magnetic tape MT, and following this burst Ba, with respect to the traveling direction, One servo pattern SP is formed by the burst Bb which is a magnetized portion of two stripes having a negative inclination angle, and this servo pattern SP is repeatedly formed in the longitudinal direction at a predetermined interval. Thus, the servo signal SS is configured.
In the present embodiment, the servo pattern SP is configured with two positive and negatively inclined stripes. However, for example, the servo pattern SP may be configured with five positive and negatively inclined stripes, Modifications can be made as appropriate, for example, by alternately forming positive and negative inclined stripes and four positive and negative inclined stripes. In FIG. 1A, the servo pattern SP is drawn relatively large on the magnetic tape MT in order to make the configuration of the servo signal SS easier to understand.

  The data band DB between the servo bands SB is also uniformly magnetized in the forward direction. The magnetic tape MT shown in FIG. 1A is an unrecorded data, and when data is recorded, a portion magnetized in the data band DB in the reverse direction or the forward direction according to the contents of the data. Will be formed.

(Positional relationship between magnetic tape and magnetic head)
Here, FIG. 1A shows the positional relationship of the magnetic head H of the magnetic tape recording / reproducing apparatus (not shown) with respect to the magnetic tape MT.
In the magnetic head H, servo signal reading elements SH for reading the servo signal SS are arranged side by side in the width direction of the magnetic tape MT at the same intervals as the intervals of the plurality of servo bands SB.
Between each servo signal reading element SH, a plurality of recording elements WH for recording signals in the data band DB are arranged side by side in the width direction of the magnetic tape MT. Are provided in two rows in the running direction of the magnetic tape.
Further, a plurality of reproducing elements RH are arranged in a line in the width direction of the magnetic tape MT between the recording elements WH.

  When recording / reproducing data on the magnetic tape MT by the magnetic head H as described above, the servo signal SS is read by the servo signal reading element SH. At this time, since the servo pattern SP of the servo signal SS is inclined with respect to the running direction of the magnetic tape MT and is formed by stripes that are not parallel to each other, the servo signal reading element SH reads the servo signal SS. The timing at which the pulses are detected differs depending on the relative positions of the magnetic tape MT and the magnetic head H in the width direction. Therefore, by controlling the position of the magnetic head H in the width direction so that the pulse reading timing is a predetermined condition, the recording element WH or the reproducing element RH is accurately arranged on a predetermined track of the data band DB. (Tracking control) can be performed.

The output (peak voltage value) when the servo signal reading element SH reads the servo signal SS depends on the change rate or change amount of the magnetic field for switching between the portion where the signal is not recorded and the portion where the signal is recorded. To do.
In this embodiment, the direction of magnetism changes greatly from the forward direction to the reverse direction at the switching portion of the servo pattern SP magnetized in the reverse direction from the portion of the ground servo band SB magnetized in the forward direction. Become. Further, the direction of magnetism greatly changes from the reverse direction to the forward direction even when the portion of the servo pattern SP magnetized in the reverse direction switches to the portion of the ground servo band SB magnetized in the forward direction. Therefore, according to this large magnetic change, the servo signal reading element SH can read the servo signal SS with a large output as shown in FIG. Therefore, the SN ratio of the read signal of the servo signal SS can be improved.

[Configuration of servo writer]
Next, a servo writer for writing the servo signal SS on the magnetic tape MT will be described. In the following description, the components of the magnetic tape MT are appropriately referred to FIG.

The servo writer 10 shown in FIG. 2 is a device for writing a servo signal SS to the servo band SB of the magnetic tape MT, and includes a delivery reel 11, a take-up reel 12, a drive device 13, a pulse generation circuit 14, a servo signal book. The insertion head 15, the control device 16, and the DC demagnetizing head 20 are provided.
Further, the servo writer 10 is equipped with a power supply device (not shown), a cleaning device for cleaning the magnetic tape MT, a verify head 17 for inspecting the written servo signal SS, and the like.

(Configuration of sending reel and take-up reel)
In the delivery reel 11, before writing the servo signal SS, the magnetic tape MT cut into the product width from the wide web original is set on a large-diameter roll pancake, and the magnetic tape is written when the servo signal SS is written. It is comprised so that MT may be sent out.
The magnetic tape MT delivered from the delivery reel 11 is guided by a guide 18 or the like and conveyed to the DC degaussing head 20, the servo signal writing head 15, and the verification head 17.
Then, the magnetic tape MT that has passed through the DC degaussing head 20, the servo signal writing head 15, and the verify head 17 is guided by the guide 18 or the like and conveyed to the take-up reel 12.
The take-up reel 12 is configured to take up the magnetic tape MT that has passed through the DC degaussing head 20, the servo signal write head 15, and the verify head 17 by being driven to rotate by the drive device 13.

(Configuration of drive unit)
The drive device 13 is a device for rotationally driving the take-up reel 12, a motor (not shown), a motor drive circuit for supplying current to the motor, and a gear for connecting the motor shaft and the take-up reel 12. Etc.
In the driving device 13, a motor current is generated by a motor driving circuit based on a motor current signal from the control device 16, and the motor current is supplied to the motor, whereby the rotational driving force of the motor is wound through the gear. It is configured to transmit to the reel 12 to drive the take-up reel 12 to rotate.

  The delivery reel 11, the take-up reel 12, the drive device 13, and the guide 18 described above correspond to the “magnetic tape traveling system” recited in the claims.

(Pulse generation circuit configuration)
The pulse generation circuit 14 is a circuit that supplies a recording pulse current PC to the servo signal write head 15 and includes various electronic components.
In this pulse generation circuit 14, based on the pulse control signal from the control device 16, the positive polarity positive pulse current PP → the zero current ZC → the positive pulse current PP → the zero current ZC is successively generated in this order, and then the predetermined pulse current is generated. A recording pulse current PC is generated by repeating a pattern that does not generate a time current (zero current ZC) (see FIG. 1C).
The pulse generation circuit 14 supplies the recording pulse current PC to a coil (not shown) of the servo signal write head 15.
The current value of the plus pulse current PP is a current value sufficient for the servo signal write head 15 to magnetize the magnetic layer of the magnetic tape MT, and the coil characteristics of the servo signal write head 15 are taken into consideration. Is set.
Further, the pulse width (time) of the plus pulse current PP can define a predetermined width in the longitudinal direction of the servo pattern SP, the traveling speed of the magnetic tape MT, the shape of the head gap of the servo signal writing head 15, etc. It is set in consideration of. Further, the predetermined time of the zero current ZC can define a predetermined interval for forming the servo pattern SP, and is set in consideration of the traveling speed of the magnetic tape MT and the like.

(Configuration of servo signal writing head)
The servo signal writing head 15 is a magnetic head for writing the servo signal SS, and includes a coil (not shown) for generating a magnetic flux and a head gap (not shown).
In the servo signal write head 15, a plurality of head gaps are arranged in a row corresponding to the positions of the servo bands SB in the width direction of the magnetic tape MT. The head gap is formed by lithography using semiconductor technology, and has a non-parallel C shape having a predetermined angle with respect to the longitudinal direction of the tape.

(Verify head configuration)
The verify head 17 is disposed downstream of the servo signal write head 15 in the magnetic tape traveling direction. The verify head 17 is a magnetic head for inspecting the servo signal SS written in the servo band SB by the servo signal writing head 15, and reads the servo signal SS with a reading element (not shown). The read signal is transmitted to the control device 16.

(Configuration of control device)
The control device 16 is a device that controls the operation of each part of the servo writer 10, and includes a CPU (Central Processing Unit), various storage devices, and the like.
The control device 16 generates a motor current signal for controlling the motor current of the drive device 13 and transmits it to the drive device 13 in order to keep the traveling speed of the magnetic tape MT when writing the servo signal SS constant. Is configured to do.

  In addition, the control device 16 sets the current value of the plus pulse current PP of the recording pulse current PC in order to set the servo signal SS defining the forward width of the servo pattern SP and a predetermined interval for forming the servo pattern SP. A pulse control signal for controlling the pulse width and generation timing is generated and transmitted to the pulse generation circuit 14. That is, the control device 16 generates the pulse pattern of the plus pulse current PP → zero current ZC → plus pulse current PP → zero current ZC (see FIG. 1C).

  Further, the control device 16 stores data such as the forward width of the servo pattern when the servo signal SS is written on the magnetic tape MT in accordance with a predetermined standard, the interval for forming the servo pattern, and the like. Based on the read signal of the servo signal SS received from the verify head 17, the forward width and interval of the servo pattern SP of the servo signal SS written by the servo signal write head 15 are detected and stored. It is configured to determine whether the servo signal SS conforms to a predetermined standard by comparing with the servo pattern data.

(Configuration of DC degaussing head)
The DC degaussing head 20 is disposed upstream of the servo signal writing head 15 in the magnetic tape traveling direction, and the servo signal SS writes the servo signal SS into the servo band SB of the magnetic tape MT. 3 is a magnetic head for magnetizing the servo band SB and the data band DB of the magnetic tape MT uniformly in the forward direction, and includes a permanent magnet 21 as shown in FIGS. ing.

The permanent magnet 21 is a U-shaped magnet, the N pole is disposed above the upper surface of the magnetic tape MT, and the S pole is disposed below the lower surface of the magnetic tape MT. The tape MT is sandwiched. The permanent magnet 21 is inclined so that the N pole and the S pole are spaced apart in the forward direction (magnetic tape traveling direction), which is one direction in the longitudinal direction of the magnetic tape MT. Specifically, an N pole is arranged on the downstream side in the magnetic tape running direction, and an S pole is arranged on the upstream side. Further, the N pole and the S pole are sufficiently spaced from both sides of the magnetic tape MT so that the N pole and the S pole do not slide with the traveling magnetic tape MT. A magnetic field (dotted arrow in FIG. 3A) is generated from the N pole toward the S pole.
The N pole and S pole of the permanent magnet 21 correspond to the first magnetic pole and the second magnetic pole in the claims.

[Operational effects of DC degaussing head]
The DC degaussing head 20 configured as described above has the following operational effects.
In the DC degaussing head 20 shown in FIGS. 3A and 3B, the N pole and the S pole of the permanent magnet 21 are arranged on both sides of the magnetic tape MT, and a magnetic field generated between the N pole and the S pole. Passes from the upper surface side to the lower surface side of the magnetic tape MT. At this time, since the N pole and the S pole are spaced apart from each other in the forward direction of the magnetic tape MT, the magnetic field passing through the magnetic tape MT acts obliquely on the magnetic tape MT. Of the magnetic field acting obliquely on the magnetic tape MT, the magnetic tape MT is magnetized in the forward direction by the forward component of the magnetic tape MT.
Accordingly, since the magnetic tape MT can be magnetized in the forward direction without bringing the magnetic pole of the permanent magnet 21 close to the magnetic tape MT, sliding between the magnetic pole and the magnetic tape MT can be prevented. Damage can be prevented. Therefore, signals and data can be recorded on the magnetic tape MT in a good recording state.

[Method of manufacturing magnetic tape]
Next, a method for manufacturing the magnetic tape MT using the servo writer 10 will be described. In the following description, the components of the magnetic tape MT are appropriately referred to FIG.

First, as shown in FIG. 2, a pancake-shaped magnetic tape MT is set as the delivery reel 11 of the servo writer 10, and the tip of the magnetic tape MT is pulled out. The leading end of the magnetic tape MT is coupled to the winding core of the take-up reel 12 via a guide 18 or the like.
In this state, the take-up reel 12 is driven to rotate by the drive device 13 so that the magnetic tape MT is taken up by the take-up reel 12, thereby causing the magnetic tape MT to travel from the delivery reel 11 toward the take-up reel 12.

The magnetic tape MT delivered from the delivery reel 11 passes through the DC degaussing head 20 so that the servo band SB and the data band DB are uniformly magnetized in the forward direction.
Specifically, as shown in FIG. 3A, in the permanent magnet 21 of the DC degaussing head 20, a magnetic field (dotted arrow in FIG. 3A) generated from the N pole to the S pole is magnetic. The tape MT passes from the upper surface side to the lower surface side. At this time, the N pole and S pole of the permanent magnet 21 are spaced apart in the forward direction of the magnetic tape MT (magnetic tape traveling direction), and the magnetic field passing through the magnetic tape MT is relative to the magnetic tape MT. Will act diagonally. Of the magnetic field applied to the magnetic tape MT, the magnetic layer of the magnetic tape MT is magnetized in the forward direction by the forward component of the magnetic tape MT.

Further, the servo signal SS is written to the servo band SB of the traveling magnetic tape MT by the servo signal write head 15 after being magnetized in the forward direction by the DC degaussing head 20.
Specifically, a recording pulse current PC of a pulse train is supplied from the control device 16 to the coil in the head gap of the servo signal writing head 15 in a predetermined pattern. In this recording pulse current PC, a plus pulse current PP → zero current ZC → plus pulse current PP → zero current ZC current appears in a predetermined cycle. In the servo signal writing head 15, when the recording pulse current PC is supplied from the pulse generation circuit 14, when the plus pulse current PP flows through the coil, the magnetic layer of the magnetic tape MT is caused by the leakage magnetic flux from the head gap. When magnetized in the forward and reverse directions and at a zero current ZC, the magnetic layer of the magnetic tape MT is not magnetized. As a result, the servo pattern SP magnetized in the reverse direction is formed in the ground servo band SB magnetized in the forward direction of the magnetic tape MT.

  Thus, after the magnetic tape MT on which the servo signal SS is written is wound around the take-up reel 12, it is cut into a tape length according to the product specifications and stored in a cartridge case or the like ( Not shown).

[Effects of servo writer and magnetic tape manufacturing method]
The method for manufacturing the servo writer 10 and the magnetic tape MT as described above has the following operational effects.
In the servo writer 10 and the method of manufacturing the magnetic tape MT using the servo writer 10, as shown in FIG. 1A, after the servo band SB of the magnetic tape MT is magnetized in the forward direction, the servo band SB is obtained. Is written in the forward direction and the reverse direction, and the servo signal SS is written. When the servo signal SS is read by the magnetic head H, the change rate and change amount of the magnetic field increase, and the servo signal SS Output increases. Thereby, since the SN ratio of the read signal of the servo signal SS is improved, the position control of the magnetic head H can be performed with high accuracy.

  In the DC degaussing head 20, the N pole and the S pole, which are respectively arranged on both sides of the magnetic tape MT, are spaced apart in the forward direction of the magnetic tape MT and are oblique to the magnetic tape MT. Since the magnetic tape MT is magnetized in the forward direction by the forward component of the magnetic tape MT among the magnetic fields acting on the magnetic field, the forward direction is applied to the magnetic tape MT even if the magnetic pole of the permanent magnet 21 is not brought close to the magnetic tape MT. Can be magnetized. As a result, sliding between the magnetic pole and the magnetic tape MT can be prevented, and damage to the magnetic tape MT can be prevented. Therefore, the above-described servo writer 10 and the magnetic tape MT manufacturing method using the servo writer 10 can manufacture a high-quality magnetic tape MT.

[Other Embodiments]
As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. 4A and 4B are configuration diagrams showing a DC demagnetizing head according to another embodiment. FIG. 4A is a side view of a configuration in which permanent magnets are arranged on both sides of a magnetic tape, and FIG. It is a side view of the structure which inclined and moved the tape.

  For example, in the present embodiment, as shown in FIGS. 3A and 3B, the magnetic tape MT is sandwiched between the N pole and the S pole of the integral U-shaped permanent magnet 21. As shown in FIG. 4 (a), the permanent magnets 21a and 21b can be arranged integrally on both sides of the magnetic tape MT so that the north pole or south pole faces the magnetic tape MT, respectively. Furthermore, an electromagnet can also be used. Similarly to the case of the permanent magnet 21 described above, the magnetic tape MT may be sandwiched between the N pole and the S pole of the integral electromagnet, and the electromagnets are integrally formed on both sides of the magnetic tape MT. You may arrange.

  The angle of the magnetic field acting obliquely with respect to the magnetic tape MT is not limited, and may be an angle at which a forward component is generated in the magnetic field so that the recording layer of the magnetic tape MT is magnetized in the forward direction. That's fine. For example, it is desirable that the magnetic field acts on the magnetic tape MT at an angle of 45 ° or more without bringing the permanent magnet 21 into contact with the magnetic tape MT.

  Further, in this embodiment, as shown in FIG. 3A, the permanent magnet 21 is tilted with respect to the magnetic tape MT running in the horizontal direction so that the N pole and the S pole are in the forward direction of the magnetic tape MT ( In the magnetic tape running direction), the magnetic tape MT is arranged in the horizontal direction between the N pole and the S pole arranged in the vertical direction as shown in FIG. 4B. By traveling obliquely, the N pole and the S pole can be spaced apart in the forward direction of the magnetic tape MT.

  In the present embodiment, as shown in FIG. 1A, the servo band SB and the data band DB of the magnetic tape MT are uniformly magnetized in the forward direction, but only the servo band SB is magnetized in the forward direction. The data band DB may be configured not to be magnetized in the forward direction.

1A and 1B are diagrams illustrating a magnetic tape according to the present embodiment, in which FIG. 1A is an enlarged plan view for explaining a magnetization state of the magnetic tape, FIG. 2B is a diagram illustrating a servo signal read from the magnetic tape, and FIG. It is the figure which showed the signal when writing. It is the block diagram which showed the servo writer of this embodiment. BRIEF DESCRIPTION OF THE DRAWINGS It is the block diagram which showed the DC demagnetizing head of this embodiment, (a) is a side view of the aspect which is magnetizing the magnetic tape, (b) is a front view of the aspect which is magnetizing the magnetic tape. FIG. 6 is a configuration diagram showing a DC demagnetization head according to another embodiment, where (a) is a side view of a configuration in which permanent magnets are arranged on both sides of the magnetic tape, and (b) is an illustration of tilting the magnetic tape with respect to the permanent magnet. It is a side view of the structure made to drive | work. It is the block diagram which showed the conventional DC demagnetizing head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Servo writer 11 Sending reel 12 Take-up reel 13 Drive apparatus 14 Pulse generation circuit 15 Servo signal write head 16 Control apparatus 20 DC demagnetizing head 21 Permanent magnet MT Magnetic tape DB Data band SB Servo band SP Servo pattern SS Servo signal

Claims (3)

A DC demagnetizing head for magnetizing a magnetic tape in one longitudinal direction,
Comprising a first magnetic pole and a second magnetic pole respectively disposed on both sides of the magnetic tape;
The DC demagnetizing head, wherein the first magnetic pole and the second magnetic pole are spaced apart from each other in the longitudinal direction of the magnetic tape. A servo writer used for manufacturing a magnetic tape in which servo signals for tracking control of a magnetic head are written in a servo band and data is recorded in a data band,
A magnetic tape running system that winds and runs the magnetic tape delivered from the delivery reel with a take-up reel;
The DC demagnetizing head according to claim 1, wherein at least the servo band of the traveling magnetic tape is magnetized in one direction in a longitudinal direction of the magnetic tape;
Servo signal writing, which is disposed downstream of the DC degaussing head in the direction of travel of the magnetic tape, writes the servo signal by magnetizing the servo band of the traveling magnetic tape in the direction opposite to the one direction. Insert head,
A servo writer characterized by comprising: A method of manufacturing a magnetic tape using the servo writer according to claim 2,
Running the magnetic tape from the delivery reel toward the take-up reel by the magnetic tape running system;
Magnetizing at least the servo band of the traveling magnetic tape in the longitudinal direction of the magnetic tape by the DC degaussing head;
Magnetizing the servo band in a direction opposite to the one direction by the servo signal writing head to write the servo signal;
The manufacturing method of the magnetic tape characterized by including.

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