Method to reduce sensitivity of a perpendicular recording head to external fields

a technology of perpendicular recording head and external field, applied in the field of magnetic disk system, can solve the problems of unwanted writing or erasure, affecting the uniformity of the flux distribution over the surface of the shield, and affecting the accuracy of the signal

Inactive Publication Date: 2006-11-02
HEADWAY TECH INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When the flux density is large enough, unwanted writing or erasing can occur.
Because of the magnetic softness of the shield materials, a small amount of external field can induce relatively large fields in the media and cause erasure of information on the media.
Due to the finite thickness and moment of the soft magnetic underlayer, flux distribution is not uniform over the surfaces of the shields.

Method used

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  • Method to reduce sensitivity of a perpendicular recording head to external fields
  • Method to reduce sensitivity of a perpendicular recording head to external fields
  • Method to reduce sensitivity of a perpendicular recording head to external fields

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Embodiment Construction

[0024] The present invention solves the problem of excessive fields at shield edges by modifying their shape to include extra tabs or to create recessed edges at their lower (ABS) edges. In the case of extra tabs, the shape of these tabs may be either triangular (as in tabs 31 in FIG. 3) or rectangular (as in tabs 41 in FIG. 4). In the case of recessed edges, the angle of recessed edges is a constant, with respect to the ABS line (as shown in FIG. 5. Typically, the angle of the slope would be between about 8 to 20 degrees and outer portion 63 should constitute less than 30% of shield width. FIG. 6 shows yet another embodiment which is a combination of tabs (71) and recessed edge (73).

[0025] In FIG. 7, the magnetic field in the media under a constant external field of 200 Oe is plotted as a function of position along the shield for a conventional rectangular shield (curve 81), a shield with triangular tab (curve 82), and a shield with a recessed edge (curve 83). It is clear that the...

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Abstract

In a read-write head, the shields can serve as magnetic flux conductors for external fields, so that they direct a certain amount of flux into the recording medium. This problem has been overcome by the addition to the shields of a pair of tabs located at the edges closest to the ABS. These tabs serve to prevent flux concentrating at the edges so that horizontal fields at these edges are significantly reduced. Said tabs need to have aspect ratios of at least 2 and may be either triangular or rectangular in shape. Alternatively, the tabs may be omitted and, instead, outer portions of the shield's lower edge may be shaped so as to slope upwards away from the ABS.

Description

RELATED PATENT APPLICATIONS [0001] This application is related to attorney docket number HT04-036B, serial number ______, filed on ______, which is herein incorporated by reference in its entirety, which is assigned to a common assignee as the instant application. FIELD OF THE INVENTION [0002] The invention relates to the general field of magnetic disk systems with particular reference to magnetic write heads for perpendicular designs and their sensitivity to external magnetic fields. BACKGROUND OF THE INVENTION [0003] As magnetic recording is pushed to higher areal densities, perpendicular recording may offer advantages in thermal stability over longitudinal recording, thus delaying arrival at the super-paramagnetic limit. Another advantage of perpendicular recording with single pole (SP) head and perpendicular media, with a soft underlayer (SUL), is the ability to produce a larger write field than that of a ring head to record on relatively thick media with high anisotropy constan...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G11B5/33G11B5/127
CPCG11B5/11G11B5/3967G11B5/1278
Inventor GUAN, LIJIEDOVEK, MORIS
Owner HEADWAY TECH INC
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