Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2000-05-02
2004-03-09
Letscher, George J. (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
Reexamination Certificate
active
06704171
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to the field of digital tape recording. More particularly, the invention relates to head lifting apparatus for digital tape systems.
2. Discussion of the Related Art
Headlift mechanisms are known to those skilled in the art. For example, a conventional headlift mechanism typically includes a headlift bracket coupled with a stepper motor (the combination herein referred to as the “headlift assembly”). The read/write transducer head of a data storage system is mounted on the bracket. The bracket is coupled with other portions of the tape drive via a head guide assembly (HGA) frame. The HGA includes the headlift assembly and the HGA frame. The stepper motor typically includes a threaded shaft that rotates to cause the head and the headlift bracket to move upwards or downwards across a digital tape. This movement positions the head over the tape's data tracks. Each data track runs along the length of the tape. Multiple data tracks are disposed vertically, one above the other, over the width of the tape. One of the key capacity limitations of tape storage systems has been that only a limited number of data tracks could be placed over the width of the tape because of the headlift assembly could not accurately place the head over the tracks.
FIG. 1
shows a portion of a tape drive including a conventional HGA
100
. The conventional HGA includes conventional stepper motor
110
, HGA frame
120
, and headlift bracket
130
. HGA guide pin
140
is mounted on HGA frame
120
to provide head alignment accuracy across the width of the tape.
Conventional stepper motor
110
includes a rotating shaft, which is typically a lead-screw
112
and a circular top surface
114
. Lead-screw
112
extends upwards from circular top surface
114
.
Headlift bracket
130
includes a platform
132
for mating with the head, and a conventional arm (not shown in
FIG. 1
) extending horizontally from the platform. The conventional arm typically has an opening and a nut configured to receive lead-screw
112
, which when fastened to the lead-screw cause the HGA to move upwards or downwards in response to movement of the lead-screw. Neither the nut nor the opening is shown in FIG.
1
. Conventional stepper motor
110
controls movement of lead-screw
112
. Any rotation about the threads of lead-screw
112
results in movement of the headlift assembly upward or downward along the screw.
HGA guide pin
140
is mated to headlift bracket
130
using a claw
150
disposed on the bracket. Claw
150
is attached to HGA frame
120
. Claw
150
engages HGA guide pin
140
and attaches HGA guide pin
140
to HGA frame
120
.
Headlift bracket
130
is adjusted so that the lifting surface
160
(the mounting surface for the transducing head) is parallel to HGA frame
120
's mounting surface plane. As shown in
FIG. 1A
, the mounting surface plane is defined at points
165
. These three mounting surfaces of the HGA are known collectively as “Datum A.” The adjustment of the lifting surface
160
relative to the mounting surface is called “adjusting azimuth and zenith.”
Returning to
FIG. 1
, once the azimuth and zenith adjustment is complete, claw
150
will generally not be parallel with HGA guide pin
140
. To overcome a potential binding of claw
150
with HGA guide pin
140
a loosely fitting claw bushing
152
is installed between the claw and the pin. In some conventional HGA designs, claw
150
includes a claw pin
154
extending upwards from the rest of the claw. Claw bushing
152
can snap onto claw pin
154
. Claw bushing
152
is allowed to pivot about claw pin
154
(i.e., rotate about claw
150
) to relieve the binding of the claw and HGA guide pin
140
.
As headlift bracket
130
moves up and down along its designated length of travel, the relationship between claw
150
and HGA guide pin
140
changes. The relationship changes because of the loose fit between HGA guide pin
140
and claw
150
at the height of claw bushing
152
that potentially results in a non-parallel condition between claw
150
and HGA guide pin
140
. When claw
150
is not parallel with HGA guide pin
140
, a first side of claw
150
can rub HGA guide pin
140
at the bottom of the headlift travel; while the opposite side of the claw can rub HGA guide pin
140
at the top end of the headlift travel. The change in contact from one side of claw
150
to the other side can cause headlift bracket
130
to rotate while lifting. Such rotation causes an undesired linear movement of the head.
Conventional headlift mechanisms typically have large lift error tolerances that can range up to approximately 450 micro-inches. However, because newer tape drives have more and narrower data tracks, as well as higher tape speeds to meet demands for increased storage, tighter headlift tolerances have been imposed. As a result, the first pass yields and final yields for building conventional HGA have become unacceptably low.
The low manufacturing yields for headlift assemblies applying the prior art approach to high speed and high storage density tape drive systems result in much higher cost. The low manufacturing yields are caused by tolerance problems arising from the non-parallel condition of claw
150
and HGA guide pin
140
. If the alignment errors for the HGA components are too large, then HGA guide pin
140
and claw
150
are subject to a binding condition during movement of the HGA components during azimuth and zenith alignment. Therefore, what is also needed is a solution that meets the above-discussed headlift accuracy requirements in a more cost-effective manner. An HGA assembly that can position the head more precisely as required by new high data capacity, high-speed tape drive systems, and still be manufactured with acceptable yields is needed
SUMMARY OF THE INVENTION
A headlift system according to the present invention includes a guide pin that is integrated with a stepper motor having a shaft, and a bracket coupled to a magnetic tape transducer head. The bracket is configured to couple with the guide pin and the stepper motor shaft to provide more accurate movement of the head than conventional headlift systems.
The stepping motor controls the rotational movement of the shaft. The shaft extends from the stepping motor along a first axis and rotates about this axis. The guide pin extends from the stepping motor in approximately the same direction as the first axis. The guide pin is spaced apart from the shaft.
The head lift system also includes a bracket. The bracket includes a head mating surface, an arm, and a bushing. The arm extends horizontally from the head-mating surface. The arm includes a first opening aligned to receive the shaft, and a second opening aligned to receive the guide pin. The bushing is disposed in the second opening. The bushing is coupled with the guide pin to limit movement of the head radially, and to limit movement of the head circumferentially relative to the shaft.
The head lift system also includes a shaft-linking element. The shaft-linking element is positioned and dimensioned for coupling with the shaft.
These and other aspects of the invention will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings.
REFERENCES:
patent: 4750067 (1988-06-01), Gerfast
patent: 4833558 (1989-05-01), Baheri
patent: RE33661 (1991-08-01), Baheri
patent: 5198947 (1993-03-01), Nayak et al.
patent: 5379170 (1995-01-01), Schwarz
patent: 5434732 (1995-07-01), Schwarz et al.
patent: 5448438 (1995-09-01), Kasetty
patent: 5793574 (1998-08-01), Cranson et al.
patent: 5982590 (1999-11-01), Kinjo et al.
Beacham C R
Letscher George J.
Morrison & Foerster / LLP
Quantum Corporation
LandOfFree
Apparatus and systems for lifting a tape drive transducer head does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and systems for lifting a tape drive transducer head, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and systems for lifting a tape drive transducer head will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3292207