The preferred embodiments are in the field of magnetic storage media drives and are more specifically directed to improving thermal conductivity of heat so as to facilitate smaller drives and faster read/write speeds in such drives.
Magnetic disk drives are used over a wide range of electronic systems, including large-scale network servers, desktop computers and workstations, portable computers, and now even in modern handheld devices such as portable digital audio players. As is well known in the art, the capacity of conventional disk drives has greatly increased over recent years, at ever decreasing cost per megabit, while at the same time the size of the drive continues to decrease. Indeed, the decrease in size permits the use of drives in smaller equipment, including the above-mentioned audio players and with likely additional applications in the future.
The decrease in disk drive size has been achieved in many ways, including the use of smaller parts and the dimensions between those parts. A relatively smaller drive includes a smaller disk or a stack of smaller disks arranged in a so-called head stack, where the axis of each disk is co-aligned and an arm is typically located between each disk as well as on top of the uppermost disk and below the lowermost disk. For example, in a head stack of two disks (i.e., an upper disk and a lower disk), then a first movable arm is supported so that its tip extends between the two disks and with a first read/write sensor assembly (or “head”) located at its upper surface and a second read/write sensor assembly located at its lower surface; with this configuration, the first sensor assembly is for read/write operations with respect to the lower side of the upper disk, and the second sensor assembly is for read/write operations with respect to the upper side of the lower disk. A second movable arm is supported so that its tip extends above the top of the upper disk and with one read/write sensor assembly located at the lower surface of that tip for read/write operations with respect to the upper side of the upper disk. Finally, a third movable arm is supported so that its tip extends below the bottom of the lower disk and with one read/write sensor assembly located at the upper surface of its tip for read/write operations with respect to the lower side of the lower disk. In the prior art, each of the three (or other number) movable arms in the disk drive are moved by a common member, sometimes referred to as an armature block or also as an E-block because in the case of three arms as just described, the cross section of the member has an “E” shape in that each of the three physical supports, corresponding to the respective three arms, protrudes from a same perpendicular structure as do the horizontal lines in the letter “E.”
Various factors such as the materials, dimensions, and proximity of the above and related components provide increasing complexities with the reduction in the size of device drives. For example, the movable arms are typically thicker metal near the area in which they connect to the E-block and then have a thinner metal suspension that extends in the direction of the disks and supports the respective sensor assembly or assemblies. Further, the size of the arms is commensurate with the size of the disks, and each sensor assembly is typically microscopic in dimensions. As another example, the entire E-block, and correspondingly the arms it supports, is rotated within an arc by a mechanism that typically includes a coil with magnets above and below the coil so that a reversible current through the coil can cause a partial rotation of the mechanism in either direction across the arc. As still another example, typically a preamplifer in the form of an integrated circuit is electrically connected to the sensor assemblies via a so-called flex unit, where in more contemporary devices the preamplifier is physically mounted in thermal communication with the side of the E-block. The preamplifier also may include fly-height circuitry that controls the distance between a read/write sensor assembly and its respective disk surface.
With all of the attributes described above, the present inventors have recognized that there are considerable thermal issues with respect to the head stack and its related components, sometimes referred to as the head stack assembly. For instance, there are various sources of heat in the confined space, including for example, power transistors in the preamplifier as well as from the coil driven mechanism that rotates the E-block. Further, with physical contact between certain components there is little, if any, air gap and, thus air is trapped and therefore is unable to efficiently release heat in such an area. In other words, there is simply little or no room for convection cooling. Various other factors also contribute to the accumulation of heat in and near the head stack assembly. With larger media, the movable arms must be longer and therefore require a greater amount of current to drive the inductance of the above-mentioned coils, thereby creating more heat. Further, the dimensions of the arms may reduce the ability to dissipate heat. As another example, the generation of heat increases with increasing data rates, such as 800 to 900 mbps in contemporary laptops. Still other examples may be appreciated by one skilled in the art.
Heat build-up in and near the head stack assembly is undesirable for many reasons. For example, long term heat exposure affects the lifespan of the unit, such as in connection with the deleterious effect that heat has on the silicon used to form the preamplifier. As another example, the accumulation of heat necessarily limits the speed at which the drive may be operated, as exceeding a determined limit will cause still more heat and affect lifespan and data integrity. In some applications, these factors may be less critical, whereas in others the demands of the marketplace are extremely high, so such factors are paramount and therefore so are the above-noted considerations. For these reasons, therefore, the present inventors seek to improve upon aspects related to the above, as is explored in connection with the preferred embodiments detailed below.