Dynamic magnetic information storage or retrieval – Head mounting – Disk record
Reexamination Certificate
2002-04-19
2004-06-08
Evans, Jefferson (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
Disk record
C360S294400
Reexamination Certificate
active
06747848
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a head gimbal assembly (HGA) with a precise positioning actuator for a head element such as a thin-film magnetic head element or an optical head element.
DESCRIPTION OF THE RELATED ART
In a magnetic disk drive apparatus, thin-film magnetic head elements for writing magnetic information into and/or reading magnetic information from magnetic disks are in general formed on magnetic head sliders flying in operation above the rotating magnetic disks. The sliders are supported at top end sections of suspensions of HGAs, respectively.
Recently, recording and reproducing density along the radial direction or along the track width direction in the magnetic disk (track density) has rapidly increased to satisfy the requirement for ever increasing data storage capacities and densities in today's magnetic disk drive apparatus. For advancing the track density, the position control of the magnetic head element with respect to the track in the magnetic disk by only a voice coil motor (VCM) has never presented enough accuracy.
In order to solve this problem, an additional actuator mechanism is mounted at a position nearer to the magnetic head slider than the VCM so as to perform fine precise positioning that cannot be realized by the VCM only. The techniques for realizing precise positioning of the magnetic head are described in for example U.S. Pat. No. 5,745,319 and Japanese patent publication No. 08180623 A.
The HGA with such a precise positioning actuator is required to have a sufficient high resonance frequency of the suspension to provide a high speed servo-operation.
In general, a load applied to the magnetic head slider is adjusted by means of a bending section additionally formed as a part of a load beam of a suspension near a base plate. Namely, the load beam at a position near the base plate is slightly bent to form the bending section so that a top end section of the load beam presses the magnetic head slider mounted toward a magnetic disk. The load applied to the magnetic head slider can be adjusted by controlling a bend angle of this bending section.
However, forming of such a bending section onto the load beam greatly lowers a resonance frequency of the whole suspension due to a complex shape of the bent load beam. Thus, the lowered resonance frequency may be laid within a frequency band used for the servo mechanism making a high speed operation of the servo difficult.
Also, if such a bending section is formed onto the load beam, the suspension will be seriously susceptible to wind resistance. Namely, side winds produced due to a high-speed rotation of the magnetic disk will be directly applied to and thus exert a large influence upon the bending section causing random vibrations of the suspension to occur. Particularly, the influence of the wind resistance becomes large in case of a recent high end HDD in which the magnetic disk rotates at a high speed of 10,000 to 15,000 rpm or more.
Furthermore, since the bending section has a low stiffness, a top end section of the suspension will receive a large impact if a shock toward its up-and-down directions (Z-directions) is applied to the suspension causing making a shock resistance of the whole suspension extremely poor.
In addition, according to the conventional HGA with a bending section for adjusting a load applied to the magnetic head slider by controlling its bent bend angle, not only the fabrication process is complicated but also a precise adjustment of the load cannot be expected. Particularly, because the load value to be adjusted decreases as the magnetic head slider becomes light in weight, any variation in the adjusted load cannot be negligible and therefore load tolerance increases.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an HGA with a precise positioning actuator for a head element, whereby a resonance frequency of the HGA can be increased.
Another object of the present invention is to provide an HGA with a precise positioning actuator for a head element, whereby wind-resistance performance of the HGA can be increased.
Further object of the present invention is to provide an HGA with a precise positioning actuator for a head element, whereby a resistance against a shock of in Z-directions can be increased.
Still further object of the present invention is to provide an HGA with a precise positioning actuator for a head element, whereby a manufacturing process of the HGA can be simplified and a load tolerance can be kept small.
According to the present invention, an HGA includes a head slider provided with at least one head element, a load beam, a flexure fixed to the load beam for determining a flying attitude of the head slider, a precise positioning actuator fixed to the head slider and supported by the flexure, for precisely positioning the at least one head element, and a load adjustment mechanism formed with the actuator, for adjusting a load imposed on the head slider.
The actuator is provided with a load adjustment mechanism for adjusting a load imposed on the head slider. Therefore, it is unnecessary that the load beam of the HGA has a bending section for imposing a load, and thus the load beam can be formed by a member with a sufficient stiffness resulting in increasing a resonance frequency of the suspension. Accordingly, a frequency band for a servo can be broadened and thus a high speed seek operation of the servo can be expected. The increased stiffness of the suspension provides improvement in a shock resistance of the HGA against a Z-direction impact.
Also, since the load beam which has a large side sectional area and receives side winds with no bending section for imposing a load, influence of wind resistance can be suppressed to a minimum. Furthermore, since the imposed load is adjusted by controlling the load adjustment mechanism instead of controlling a bending angle of a bending section, not only a manufacturing process of the HGA can be simplified and a manufacturing cost of the HGA can be reduced, but also the imposed load can be adjusted with a high accuracy and a small tolerance.
It is preferred that the load adjustment mechanism is formed directly underneath a load point onto the head slider.
It is also preferred that a projection or a dimple formed on the load beam functions as the load point.
It is preferred that the load adjusting means includes a spring plate section for controlling the load imposed on the head slider, and that one end of the load adjusting means is a free end.
It is further preferred that the actuator is formed from a multilayer plate member. In this case, it is more preferred that the multilayer plate member includes a first thin metal plate layer, a resin layer laminated on the first thin metal plate layer and a second thin metal plate layer laminated on the resin layer, and that the spring plate section is formed by a part of the first or second thin metal plate layer.
It is also preferred that the actuator is formed from a single-layer metal plate member. In this case, it is more preferred that the load adjustment mechanism includes the single-layer metal plate member and a spacer laminated on the single-layer metal plate member, and that the spring plate section is formed by a part of the single-layer metal plate member.
It is further preferred that the actuator is unitarily formed with the flexure, or individually formed from the flexure.
Preferably, the load beam is a straight shaped load beam to have a high stiffness. In this case, the load beam may consist of a single plate member. The load beam may have no load adjustment mechanism for adjusting a load imposed on the head slider.
It is also preferred that the HGA further includes a back-bending section capable of bending a part of the HGA at the time of mounting of the HGA to an HDD.
It is preferred that the actuator includes a pair of movable arms each formed by a multilayer plate member or a single-layer metal plate member that is substantially in parallel with a side surface of the head slider, top end s
Kasajima Tamon
Shiraishi Masashi
Burns Doane Swecker & Mathis L.L.P.
Evans Jefferson
SAE Magnetics (H.K. ) Ltd.
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