Dynamic magnetic information storage or retrieval – Head mounting – For moving head into/out of transducing position
Reexamination Certificate
1999-05-14
2001-04-03
Klimowicz, William (Department: 2754)
Dynamic magnetic information storage or retrieval
Head mounting
For moving head into/out of transducing position
C073S865600, C324S212000
Reexamination Certificate
active
06212045
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to magnetic head and disk testers, and in particular, to a method and apparatus for loading a magnetic head onto a magnetic disk accurately and smoothly, so as to avoid damage to the magnetic head and the magnetic disk during the loading operation.
BACKGROUND OF THE INVENTION
A magnetic head and disk tester is an instrument that is used for testing the characteristics of magnetic heads and disks. Tester parameters may include signal-to-noise ratio, bit error rate, and the like. A tester typically includes two main assemblies, an electro-mechanical assembly that performs movements of a head with respect to a disk, and an electronic assembly that is responsible for measurements, calculations, and analysis of the measured data. The electro-mechanical assembly of the tester is known as a spinstand. The spinstand generally simulates the motions of the head with respect to the disk that occur in, for example, a hard disk drive. The spinstand includes a support and rotational driver for the magnetic disk. The spinstand also includes an assembly of components which effects movement and placement of a magnetic head relative to the rotating, or spinning, magnetic disk, often referred to as a head-loading mechanism. Since the magnetic head and disk are very fragile by their nature, it is important that the magnetic head and disk never actually come into physical contact during operation. However, the magnetic head and disk are positioned in extremely close proximity to each other under such conditions to support magnetic read and write operations. Therefore, precise placement of the magnetic head relative to the magnetic disk is essential to avoid damaging contact between the two.
In a typical spinstand configuration, the magnetic head is part of a head-gimbal assembly which disposes the magnetic head over the magnetic disk (but separated by aerodynamic forces) and is moved under the control of the head-loading mechanism.
FIG. 1
shows a typical prior art head-gimbal assembly (HGA)
15
, which includes a slider
10
disposed at a distal end of an elongated resilient suspension member
12
and a planar mounting portion
14
formed at its proximal end. Generally the suspension member
12
extends along a suspension axis S. The suspension axis S is angularly offset with respect to the planar portion
14
. Slider
10
includes the magnetic head read and write elements of head-gimbal assembly
15
. Disposed along the underside of suspension member
12
, typically, are electrical wires
16
which carry read and write data signals to and from the magnetic head. In operation, the head-gimbal assembly
15
is secured to a cartridge, which in turn is secured to and manipulated by head-loading mechanism components to accomplish loading of the magnetic head over/onto the spinning magnetic disk.
To effect loading, the head-loading mechanism advances the slider toward a magnetic medium-bearing surface of the spinning disk. The resilience characteristic of the suspension is selected so that the slider is spring-biased toward the disk but kept separated form that disk due to air flow between the head and the spinning disk. The separation between the head and disk surface is referred to in art as the “flying height”.
Thus, for the configuration of
FIG. 1
, suspension member
12
biases slider
10
toward the magnetic disk. When slider
10
is positioned near the spinning magnetic disk, an “air bearing” is formed between the slider
10
and the magnetic disk, and aerodynamic forces on the slider
10
counter the bias of the suspension member
12
, causing the slider
10
to remain suspended just above the rotating magnetic disk, separated by a predetermined small gap (or “flying height”) between slider
10
and the disk surface. The actual positioning of slider
10
relative to the magnetic disk, and the associated manipulation of the suspension member
12
are accomplished by various components of the head-loading mechanism. For example, in various prior art embodiments, arms or bars are used to control the suspension member
12
as the slider
10
is positioned near, or loaded onto, the disk.
In a typical prior art head-loading mechanism, the mounting portion
14
of head-gimbal assembly
15
is secured to a flat surface of a rigid block, known as a cartridge. The cartridge (with the head-gimbal assembly attached) is first affixed to a mating surface of the head-loading mechanism, for example using a pneumatic coupling. As part of the loading operation, the head-loading mechanism is then moved close to a magnetic disk and the slider
10
(and its read and write elements) is positioned over the disk such that the slider remains close to the disk, but is not brought into close proximity with the disk surface at this point. The disk may or may not be spinning during this part of the loading operation, depending on the particular design and configuration of the head and disk. The subsequent loading and testing operations depend on the type of head-loading mechanism incorporated by the spinstand of the tester. Those loading and test operations generally include lowering the head toward the disk to establish the suspension-air bearing force balance (i.e. the “loading”) followed by moving the head through a series of predetermined test positions relative to the disk and reading and writing data (i.e. the “testing”).
A portion of a prior art spinstand head-loading mechanism
20
is shown
FIG. 2
as an example of such mechanisms. A head-gimbal assembly of the type shown in
FIG. 1
, and a cartridge
22
are mounted on a mating surface of the head loading mechanism
20
of the spinstand so that the slider
10
is opposite but grossly spaced apart, from the upper surface of spinning magnetic disk
26
. The suspension member
12
is angled downward toward disk
26
, with electrical wires
16
disposed on the underside of suspension member
12
. The mounting portion
14
of the suspension member
12
is secured to the cartridge
22
which is secured in turn to head loading mechanism
20
. In this exemplary prior art configuration, a metal arm
24
is disposed under the suspension member
12
such that its upper surface engages the underside of suspension member
12
between the slider
10
and portion
14
, ensuring that slider
10
is significantly separated from disk
26
. Arm
24
is movable in the X and Y directions, as illustrated in FIG.
2
. In operation after the disk
26
is spinning, and with arm
24
in its extended position so that it underlies the suspension member
12
, and with slider
10
positioned over disk
26
(all as shown in FIG.
2
), arm
24
is lowered until slider
10
approaches its flying height and suspension member
12
separates from arm
24
. Then arm
24
is retracted and testing begins. This prior art configuration has several significant problems. First during the loading operation, slider
10
moves on an arc and therefore the motion can be controlled more accurately and smoothly if arm
24
contacts suspension member
12
at a point close to slider
10
. However, that is problematic because since suspension
12
is originally at an angle to mounting portion
14
of the head, arm
24
can not be positioned very close to slider
10
, as this would cause arm
24
to contact and damage slider
10
as cartridge
22
(with the attached head-gimbal assembly) is installed on head loading mechanism
20
. During installation of cartridge
22
on head loading unit
20
, arm
24
remains in its position and therefore lifts suspension element
12
as cartridge
22
makes firm contact with head loading mechanism
20
. Again, because suspension
12
is originally at an angle to mounting portion
14
of the head-gimbal assembly, and arm
24
is made of metal, this operation typically causes arm
24
to scratch the side of suspension
12
where it contacts arm
24
. In some types of heads, this results in damage to electrical wires
16
underneath suspension
12
.
Another form of prior art spinstand head-loading mechanism is shown in FIG.
Guzik Technical Enterprises
Klimowicz William
McDermott & Will & Emery
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