Encased E-block

Details Encased E-block Encased E-block

2000-03-30

2004-11-02

Tupper, Robert S. (Department: 2652)

Dynamic magnetic information storage or retrieval

Head mounting

For shifting head between tracks

Reexamination Certificate

active

06813120

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to the field of mass storage devices. More particularly, this invention relates to an apparatus and method for producing a stiffer of the E-block or actuator assembly in a disc drive.
BACKGROUND OF THE INVENTION
One key component of any computer system is a device to store data. Computer systems have many different places where data can be stored. One common place for storing massive amounts of data in a computer system is on a disc drive. The most basic parts of a disc drive are a disc that is rotated, an actuator that moves a transducer to various locations over the disc, and electrical circuitry that is used to write and read data to and from the disc. The disc drive also includes circuitry for encoding data so that it can be successfully retrieved and written to the disc surface. A microprocessor controls most of the operations of the disc drive as well as passing the data back to the requesting computer and taking data from a requesting computer for storing to the disc.
The transducer is typically placed on a small ceramic block, also referred to as a slider, that is aerodynamically designed so that it flies over the disc. The slider is passed over the disc in a transducing relationship with the disc. Most sliders have an air-bearing surface (“ABS”) which includes rails and a cavity between the rails. When the disc rotates, air is dragged between the rails and the disc surface causing pressure, which forces the head away from the disc. At the same time, the air rushing past the cavity or depression in the air bearing surface produces a negative pressure area. The negative pressure or suction counteracts the pressure produced at the rails. The slider is also attached to a load spring which produces a force on the slider directed toward the disc surface. The various forces equilibrate so the slider flies over the surface of the disc at a particular desired fly height. The fly height is the distance between the disc surface and the transducing head, which is typically the thickness of the air lubrication film. This film eliminates the friction and resulting wear that would occur if the transducing head and disc were in mechanical contact during disc rotation. In some disc drives, the slider passes through a layer of lubricant rather than flying over the surface of the disc.
Information representative of data is stored on the surface of the storage disc. Disc drive systems read and write information stored on tracks on storage discs. Transducers, in the form of read/write heads attached to the sliders, located on both sides of the storage disc, read and write information on the storage discs when the transducers are accurately positioned over one of the designated tracks on the surface of the storage disc. The transducer is also said to be moved to a target track. As the storage disc spins and the read/write head is accurately positioned above a target track, the read/write head can store data onto a track by writing information representative of data onto the storage disc. Similarly, reading data on a storage disc is accomplished by positioning the read/write head above a target track and reading the stored material on the storage disc. To write on or read from different tracks, the read/write head is moved radially across the tracks to a selected target track.
There are two basic types of actuators: linear and rotary. A linear actuator positions the head assembly linearly along a radius of the disk. A rotary actuator, functions much like the tone-arm on a record player, with the actuator positioning the head assembly along an arc over the disc surface. A rotary actuator consists of several components: an E-block assembly, one or more transducer head assemblies, and circuitry for carrying power and signals to and from the transducer head assemblies. The E-block assembly includes one or more arms attached at one end of the E-block, and a yoke which carries a voice coil attached at the other end of the E-block. The E-block also has a bore opening therein for locating a pivot cartridge to allow rotary movement of the E-block assembly. The focus of this invention is on the component referred to as an E-block assembly. The E-block assembly is also commonly referred to as a comb or comb assembly. Specifically, the invention relates to the construction and method of manufacture of E-block assemblies.
Disc drives and their various components are manufactured and marketed in a world wide market where the cost of a disc drive system and its attendant components is a critical parameter in achieving sales of the product. The cost includes factors such as the raw component material, processing (forming, packaging, handling, etc.), recycling of scrap and process wastes, product development, testing, product life, and system performance. Minimizing the cost of a disc drive and its components, such as E-block assemblies, thus encompasses a wide range of design and manufacturing issues.
The material of the component and the method of producing the component clearly has an effect on the cost of the component. Like all manufacturing decisions, the selection of material and method of manufacture requires a tradeoff of costs and advantages to obtain the desired product performance at the lowest cost possible. The parameters for selecting a material and method of manufacture for an E-block of comb assembly in a disc drive can be grouped into three main areas:
1) material and finished product performance,
2) manufacturability, and
3) life expectancy.
Product performance in the disc drive area has several constant goals. Some of the constant goals that effect disc drives include lower access times, increased data capacity and lower use of power by the disc drive. Access time is the amount of time needed to read data from the disc of the disc drive. In most instances, the three manufacturing parameters listed above are optimized to improve the access performance of the disc drive. In other instances, power consumption may be minimized for a given access performance, or access performance may be maximized for a given power consumption.
For disc drive systems, it is desired to maximize the E-block assembly stiffness and minimize the system inertia, because increased stiffness and reduced inertia result in improved access performance (i.e., faster access time and smaller power requirements). A stiffer system will respond faster, as greater stiffness minimizes “settle” time at the end of a track access to a desired target track location. The faster a system “settles”, the faster the head assembly can read or write data on the disk at the target track. A low inertia allows an E-block assembly, to be moved quickly from one location to another with a minimum of power consumption. Moving a rotary actuator requires application of torque to the E-block or comb assembly. Torque can be thought of as application of a force at a distance from the axis of rotation of a body. In the instance of an E-block or comb assembly, the force is applied at a distance from the rotatory axis of a pivot cartridge within the bore of the E-block. Torque can also be expressed in terms of inertia of a body as shown in the below listed formula:
T
=(
J
)×(∝)
where
T=torque
J=inertia of the E-block or comb assembly
∝=angular acceleration of the E-block or comb assembly
From the above formula, it can be seen that reducing the inertia of the E-block or comb assembly results in a lower torque requirement to achieve the same angular acceleration. Lower torque also means less power consumption.
Several mechanical properties determine the stiffness and inertia of a system. These properties are material density, flexural modulus, and specific flexural modulus. A low material density is desired because a low density allows more material to be used to improve the stiffness of the E-block, while maintaining low mass (and thus low inertia). A low material density can reduce cost by eliminating the need for incorporating weight reducing holes into th

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