Magnetic tape device and head tracking servo method

Abstract

The magnetic tape device includes: a magnetic tape; and a servo head, in which the servo head is a TMR head, the magnetic tape includes a non-magnetic support, and a magnetic layer including ferromagnetic powder, a binding agent, and fatty acid ester on the non-magnetic support, the magnetic layer includes a servo pattern, full widths at half maximum of spacing distribution measured by optical interferometry regarding a surface of the magnetic layer before and after performing a vacuum heating with respect to the magnetic tape are greater than 0 nm and equal to or smaller than 7.0 nm, and a difference between a spacing measured by optical interferometry regarding the surface of the magnetic layer after performing the vacuum heating with respect to the magnetic tape and a spacing measured before performing the vacuum heating is greater than 0 nm and equal to or smaller than 9.0 nm.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority under 35 U.S.C 119 to Japanese Patent Application No. 2016-254445 filed on Dec. 27, 2016. The above application is hereby expressly incorporated by reference, in its entirety, into the present application.BACKGROUND OF THE INVENTION1. Field of the Invention[0002]The present invention relates to a magnetic tape device and a head tracking servo method.2. Description of the Related Art[0003]Magnetic recording is used as a method of recording information in a recording medium. In the magnetic recording, information is recorded on a magnetic recording medium as a magnetized pattern. Information recorded on a magnetic recording medium is reproduced by reading a magnetic signal obtained from the magnetized pattern by a magnetic head. As a magnetic head used for such reproducing, various magnetic heads have been proposed (for example, see JP2004-185676A).SUMMARY OF THE INVENTION[0004]An increase in recording capac...

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Benefits of technology

[0010]First, a servo head reads a servo pattern to be formed in a magnetic layer (that is, reproduces a servo signal). A position of a magnetic head in a magnetic tape device is controlled in accordance with a value obtained by reading the servo pattern. Accordingly, in a case of transporting the magnetic tape in the magnetic tape device for recording and / or reproducing information, it is possible to increase an accuracy of the magnetic head following the data track, even in a case where the position of the magnetic tape is changed. For example, even in a case where the position of the magnetic tape is changed in the width direction with respect to the magnetic head, in a case of recording and / or reproducing information by transporting the magnetic tape in the magnetic tape device, it is possible to control the position of the magnetic head of the magnetic tape in the width direction in the magnetic tape device, by performing the head tracking servo. By doing so, it is possible to properly record information in the magnetic tape and / or properly reproduce information recorded on the magnetic tape in the magnetic tape device.

[0013]A magnetoresistance effect which is an operating principle of the MR head such as the TMR head is a phenomenon in which electric resistance changes depending on a change in magnetic field. The MR head detects a change in leakage magnetic field generated from a magnetic recording medium as a change in resistance value (electric resistance) and reproduces information by converting the change in resistance value into a change in voltage. In a case where the TMR head is used as the servo head, the TMR head detects a change in leakage magnetic field generated from a magnetic layer in which the servo pattern is formed, as a change in resistance value (electric resistance) and reads the servo pattern (reproduces a servo signal) by converting the change in resistance value into a change in voltage. It is said that a resistance value of the TMR head is generally high, as disclosed in a paragraph 0007 of JP2004-185676A, but occurrence of a significant decrease in resistance value in the TMR head may cause a decrease in sensitivity of the TMR head, thereby resulting in a decrease in signal intensity of a servo signal reproduced by the servo head and a decrease in SNR accompanied with that. Accordingly, the accuracy of the head position controlling of the head tracking servo may decrease.

[0015]With respect to this, as a result of more intensive studies after finding the phenomenon described above, the inventors have newly found that such a significant decrease in resistance value can be prevented by using a magnetic tape which will be described later as the magnetic tape.

[0033]According to one aspect of the invention, it is possible to prevent occurrence of a significant decrease in resistance value in the TMR head, in a case of reading a servo pattern of the magnetic layer of the magnetic tape by the TMR head.

Problems solved by technology

However, as the recording density increases, a magnetic signal (specifically, a leakage magnetic field) obtained from a magnetic layer tends to become weak.

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