Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
1999-05-13
2001-08-14
Klimowicz, William (Department: 2754)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
Reexamination Certificate
active
06275361
ABSTRACT:
BACKGROUND OF THE INVENTION
The application relates to systems and methods for protecting magnetoresistive (MR) heads from damage caused by electrostatic discharge (ESD).
MR heads (also know as MR recording heads, MR sensors and MR elements) are typically used in magnetic storage drives to read data from and write data to magnetic storage disks. MR heads are characterized by a high sensitivity to damage caused by ESD. ESD typically is not a significant concern after a magnetic storage drive has been finally assembled because the MR head and other drive components are contained within a housing that shields the MR head from sources of ESD. On the other hand, ESD is a significant concern before the magnetic storage drive has been assembled (e.g., during manufacture and testing) because the MR head is exposed to many sources of ESD during this time.
A MR head typically is protected prior to final assembly by shorting the leads of the MR head. The MR head leads, however, must be unshorted during testing and prior to final assembly of the magnetic storage drive. Many MR head shorting techniques have been proposed. For example, shorting leads that must be manually connected to and disconnected from the MR head have been proposed. In another approach, Arya et al. (U.S. Pat. No. 5,644,454) has proposed an ESD protection system that includes a shorting bar that automatically shorts the MR head when a load beam on which the MR head is mounted bends beyond a certain angle.
SUMMARY OF THE INVENTION
The invention relates to a scheme for protecting a MR head against ESD. In accordance with this inventive scheme, the MR head may be automatically and repeatedly shorted (and consequently disabled) whenever the MR head is not required to be operable (e.g., any time after final installation or during testing). The MR head may be coupled to a support assembly that is configured to connect to an actuator assembly
In one aspect of the invention, the support assembly comprises a shorting mechanism that automatically shorts the MR head upon disconnection of the support assembly from the actuator assembly, regardless of the orientation of the support assembly, and automatically unshorts the MR head upon connection of the support assembly to the actuator assembly.
In another aspect, the invention features a support assembly that comprises a deformable surface characterized by a relaxed state in which the MR head is shorted and a deformed state the MR head is unshorted, wherein the MR head may be repeatedly shorted and unshorted by repeatedly relaxing and deforming the deformable surface.
In another aspect, the invention features a support assembly that comprises a deformable surface carrying first and second inputs configured to be coupled electrically to the MR head, wherein the two support assembly inputs are shorted together when the deformable surface is relaxed and are unshorted when the deformable surface is deformed.
Embodiments may include one or more of the following features.
The support assembly inputs may be unshorted by longitudinally stretching the deformable surface, by bending the deformable surface, or by deforming a region of the deformable surface in the vicinity of the support assembly inputs (e.g., by deforming a region of the deformable surface located between the support assembly inputs).
The deformable surface preferably is elastically deformable. The deformable surface preferably comprises an electrically insulating material. The deformable surface may comprise an elastically deformable polymeric material (e.g., polyimide). The deformable surface may comprise more than one material layer.
The relaxed state of the deformable surface may be characterized by a closed electrical connection between all of the pads of the MR head and the deformed state of the deformable surface is characterized by an open electrical connection between all of the pads of the MR head.
The deformable surface may carry one or more additional inputs configured to be coupled electrically to the MR head, wherein all of the support assembly inputs are shorted together when the deformable surface is relaxed and are unshorted when the deformable surface is deformed.
Among the advantages of the invention are the following. The invention enables an MR head to be repeatedly and easily shorted and unshorted. This feature enables the MR head to be readily unshorted when the MR head must be operable (e.g., during testing and after final assembly), while automatically shorting, and thereby protecting, the MR head against ESD at other times. The MR head be unshorted and shorted automatically as the head support assembly is loaded into and unloaded from an appropriately configured fixture. The inventive shorting mechanism is incorporated into the head support assembly and therefore provides compact, cost-effective ESD protection in a way that is relatively easy to implement in an automated assembly process. The shorting mechanism may be built into the head support assembly at the time the support assembly is manufactured. No additional devices are needed to short and unshort the MR head.
Other features and advantages will become apparent from the following description, including the drawings and the claims.
REFERENCES:
patent: 5465186 (1995-11-01), Bajorek et al.
patent: 5491605 (1996-02-01), Hughbanks et al.
patent: 5638237 (1997-06-01), Phipps et al.
patent: 5644454 (1997-07-01), Arya et al.
patent: 5699212 (1997-12-01), Erpelding et al.
patent: 5710682 (1998-01-01), Arya et al.
patent: 5812349 (1998-09-01), Shouji et al.
patent: 5877933 (1999-03-01), Johansen et al.
patent: 5963415 (1999-10-01), Johansen
patent: 5991121 (1999-11-01), Kanda
patent: 6075676 (2000-06-01), Hiraoka et al.
Goceman Ferouh
Wallash Al
Fish & Richardson P.C.
Klimowicz William
Maxtor Corporation
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