Self-heating disk drive

Disclosed is a self-heating disk drive that comprises a voice coil motor (VCM), a spindle motor, and a temperature sensor. The VCM includes a VCM coil and the VCM is configured to move an actuator having a head attached to a distal end of the actuator. The spindle motor includes a plurality of spindle coils to spin a disk of the disk drive. The temperature sensor is used to read an internal temperature of the disk drive. Circuitry is configured to: command the application of current to the VCM coil without loading the head onto the disk and to the spindle coils of the spindle motor in a manner so as not to spin the disk; and, if the internal temperature reading reaches a pre-determined spindle temperature, the spindle motor is allowed to spin-up the disk.

BACKGROUND

1. Field of the Invention

The present invention relates to a self-heating disk drive.

2. Description of the Prior Art and Related Information

Today, computing devices such as personal computers, personal digital assistants, cell-phones, etc., are routinely used at work, at home, and everywhere in-between. Computing devices advantageously enable the use of application specific software, file sharing, the creation of electronic documents, and electronic communication and commerce through the Internet and other computer networks. Typically, each computing device has a storage peripheral such as a disk drive.

A huge market exists for disk drives for mass-market computing devices, such as desktop computers and laptop computers, as well as for small form factor (SFF) disk drives for use in mobile computing devices (e.g. personal digital assistants (PDAs), cell-phones, digital cameras, etc.). To be competitive, a disk drive should be relatively inexpensive and provide substantial capacity, rapid access to data, and reliable performance.

Typically, the main assemblies of a disk drive are a head disk assembly (HDA) and a printed circuit board assembly (PCBA). The head disk assembly includes an enclosure including a base and a cover, at least one disk having at least one recording surface, a spindle motor for causing each disk to rotate, and an actuator arrangement. The PCBA generally includes circuitry for processing signals and controlling operations in the disk drive.

An actuator arrangement that is commonly used in hard disk drives is a rotary actuator arrangement included as part of a head stack assembly (HSA) that includes a collection of elements of the head disk assembly. The collection typically includes certain prefabricated subassemblies and certain components that are incorporated into the head disk assembly. For example, a prefabricated head stack assembly (HSA) may include a pivot bearing cartridge, a rotary actuator arrangement, permanent magnets and an arrangement for supporting the magnets to produce a magnetic field for a voice coil motor (VCM).

The rotary actuator arrangement of the HSA may also include a coil, forming another part of the VCM, an actuator body having a bore through it, and a plurality of arms projecting parallel to each other and perpendicular to the axis of the bore. The rotary actuator arrangement of the HSA may also include head gimbal assemblies (HGAs) that are supported by the actuator arms. Each HGA typically includes a load beam and a head supported by the load beam. The head is positioned over a track on a recording surface of the disk to write or read data to or from the track, respectively.

As disk drives are being utilized more and more with mobile devices (e.g. PDAs, cell-phones, etc.), disk drives are increasingly being subjected to very cold operating environments. For example, it is not uncommon for cell-phones and PDAs to be utilized in below freezing environments.

Unfortunately, if a disk drive is powered on while operating in a very cold or freezing environment, damage may occur to components of the disk drive, and/or disk drive performance may be severely compromised. For example, at low temperatures, there is poor lube mobility associated with the spindle motor, and read/write heads typically perform poorly.

There is therefore a need for an effective, efficient means to self-heat a disk drive.

SUMMARY

The present invention relates to a self-heating disk drive.

In one embodiment of the present invention, a self-heating disk drive comprises a voice coil motor (VCM), a spindle motor, and a temperature sensor. The VCM includes a VCM coil, and the VCM is configured to move an actuator having a head attached to a distal end of the actuator. The spindle motor includes a plurality of spindle coils to spin a disk of the disk drive. The temperature sensor is used to read an internal temperature of the disk drive. Circuitry is configured to: command the application of current to the VCM coil without loading the head onto the disk and to the spindle coils of the spindle motor in a manner so as not to spin the disk; and, if the internal temperature reading reaches a pre-determined spindle temperature, the spindle motor is allowed to spin-up the disk.

In another embodiment of the present invention, a method is disclosed to provide a self-heating disk drive. The disk drive includes a voice coil motor (VCM) having a VCM coil, in which the VCM is used to move an actuator having a head attached to a distal end of the actuator, and a spindle motor having a plurality of spindle coils that is used to spin a disk. The method disclosed comprises: applying current to the VCM coil without loading the head onto the disk and to the spindle coils of the spindle motor in a manner so as not to spin the disk; and, if an internal temperature reaches a pre-determined spindle temperature, allowing the spindle motor to spin-up the disk.

In yet another embodiment of the present invention, a disk drive is disclosed that includes a voice coil motor (VCM) having a VCM coil, in which the VCM is configured to move an actuator having a head attached to a distal end of the actuator, and a spindle motor having a plurality of spindle coils that is used to spin a disk. A processor-readable medium is also disclosed, the medium having stored thereon instructions, which, when executed by a processor, cause the processor to perform the following operations comprising: continuously monitoring an internal temperature of the disk drive; applying current to the VCM coil without loading the head onto the disk and to the spindle coils of the spindle motor in a manner so as not to spin the disk; and, if the internal temperature reaches a pre-determined spindle temperature, allowing the spindle motor to spin-up the disk.

In one other embodiment, a method is disclosed to provide a self-heating disk drive in which the disk drive includes a spindle motor having a plurality of spindle coils to spin a disk and a temperature sensor to read an internal temperature of the disk drive. The method disclosed comprises: commanding the application of current to the spindle coils of the spindle motor in a first out-of-phase manner such that the spindle motor generates excess heat in spinning the disk; monitoring the internal temperature; and if the internal temperature reaches a pre-determined temperature, commanding the application of current to the spindle coils of the spindle motor in a more power-efficient manner than the first out-of-phase manner.

The foregoing and other features of the invention are described in detail below and are set forth in the appended claims.

DETAILED DESCRIPTION

With reference toFIG. 1,FIG. 1is a perspective view illustrating the principal mechanical components of an example of a disk drive100that may be utilized with embodiments of the invention. The disk drive100comprises a head disk assembly (HDA)144and a printed circuit board assembly (PCBA)114. The HDA144includes a disk drive enclosure comprising a base116and a cover117attached to the base116that collectively house a disk stack123that includes one or a plurality of magnetic disks (e.g. disks46), a spindle motor113attached to the base116for rotating the disk stack123, a head stack assembly (HSA)120, and a pivot bearing cartridge184that rotatably supports the HSA120on the base116. The spindle motor113typically rotates the disk stack123at a relatively constant angular velocity. In one embodiment, spindle motor113may be a three-phase motor having three separate coil windings, as is known in the art.

The HSA120comprises a swing-type or rotary actuator assembly130, at least one head gimbal assembly (HGA)110, and a flex circuit cable assembly180. The rotary actuator assembly130includes a body portion140, at least one actuator arm160cantilevered from the body portion140, and a VCM coil150cantilevered from the body portion140in an opposite direction from the actuator arm160. The actuator arm160supports the HGA110that, in turn, supports the head(s). The flex cable assembly180may include a flex circuit cable and a flex clamp159. Further, flex cable assembly180may include a temperature sensor181mounted to or within the flex circuit cable. Alternatively, a temperature sensor may be mounted on the PCBA114facing the HDA144surface.

The HSA120is pivotally secured to the base116via the pivot-bearing cartridge184so that the head at the distal end of the HGA110may be moved over the surfaces of the disks46. The pivot-bearing cartridge184enables the HSA120to pivot about a pivot axis, shown inFIG. 1at reference numeral182. The storage capacity of the HDA144may be increased by, for example, increasing the track density (the TPI) on the disks46and/or by including additional disks46in the disk stack123and by an HSA120having a vertical stack of HGAs110supported by multiple actuator arms160.

The “rotary” or “swing-type” actuator assembly comprises body portion140that rotates on the pivot bearing184cartridge between limited positions, VCM coil150that extends from body portion140to interact with one or more permanent magnets192mounted to back irons170,172to form the voice coil motor (VCM), and actuator arm160that supports HGA110. The VCM causes the HSA120to pivot about the actuator pivot axis182to cause the read/write heads or transducers thereof to sweep radially over the disk(s)46.

Turning toFIG. 2,FIG. 2is a simplified block diagram of the previously-described disk drive100, illustrating particular components of PCBA114and HDA144, in which embodiments of the invention may be practiced. As shown inFIG. 2, disk drive100may be connected to a host computing device36. Computing device36may be a desktop computer, a laptop computer, a mobile computing device (e.g., a personal digital assistant (PDA), camera, cell-phone, auto-navigation system, etc.), or any type of computing device utilizing a disk drive. Disk drive100comprises head disk assembly (HDA)144and PCBA114.

As previously described, HDA144may comprise: one or more disks46for data storage (four are shown); a spindle motor113for rapidly spinning each disk46on a spindle48; actuator assembly130, having actuator arms160for moving a plurality of heads64in unison over each disk46. The heads64are connected to a preamplifier42via cable assembly180for reading and writing data on the disks46. Preamplifier42is connected to channel circuitry in PCBA114via read data line92and write data line90.

In one embodiment, PCBA114comprises a read/write channel68, servo controller98, host interface disk controller (HIDC)74, voice coil motor driver102, spindle motor driver (SMD)103to drive a three-phase spindle motor113, and several memory arrays—buffer or cache memory82, RAM108, and non-volatile memory106.

Host-initiated operations for reading and writing data in disk drive100may be executed under control of microprocessor84connected to controllers and memory arrays via buses86and96. Program code executed by microprocessor84may be stored in non-volatile memory106and random access memory RAM108. Program overlay code may be stored on reserved tracks of disks46and may also be loaded into RAM108as required for execution.

During disk read and write operations, data transferred by preamplifier42may be encoded and decoded by read/write channel68. During read operations, channel68preferably decodes data into digital bits transferred on an NRZ bus96to HIDC74. During write operations, HIDC provides digital data over the NRZ bus to channel68, which encodes the data prior to its transmittal to preamplifier42. Preferably, channel68employs PRML (partial response maximum likelihood) coding techniques.

HIDC74includes a disk controller80for formatting and providing error detection and correction of disk data and other disk drive operations, host interface controller76for responding to commands from host36, buffer controller78for storing data which is transferred between disks46and host36, and microprocessor84. The controllers in HIDC74may provide automated functions, which assist the microprocessor84in controlling disk operations.

A servo controller98provides an interface between microprocessor84and actuator assembly130and spindle motor113. Microprocessor84can command logic in servo controller98to position the actuator assembly130using a VCM driver102and to precisely control the rotation of spindle motor113with a spindle motor driver103.

Disk drive100may employ a sampled servo system in which equally spaced servo wedge sectors (termed “servo wedges”) are recorded on each track of each disk46. Data sectors are recorded in the intervals between servo sectors on each track. Servo sectors are sampled at regular intervals to provide servo position information to microprocessor84. Servo sectors are received by channel68, and are processed by servo controller98to provide position information to microprocessor84via bus86.

In one embodiment, circuitry of the disk drive, such as microprocessor84, may operate under the control of a program or routine to execute methods or processes in accordance with embodiments of the invention related to providing a self-heating disk drive. For example, such a program may be implemented in software or firmware (e.g., stored in non-volatile memory106or other locations) and may be implemented by microprocessor84or other circuitry. For example, in one embodiment, non-volatile memory may include self-heating control code107to implement aspects of the invention hereinafter discussed.

Components of the various embodiments of the invention may be implemented as hardware, software, firmware, microcode, or any combination thereof. When implemented in software, firmware, or microcode, the elements of the embodiments of the present invention are the program code or code segments that include instructions to perform the necessary tasks. A code segment may represent a procedure, a function, a subprogram, a program, a routine, a subroutine, a module, a software package, a class, or any combination of instructions, data structures, or program statements.

The program or code segments may be stored in a processor-readable medium or transmitted by a data signal embodied in a carrier wave, or a signal modulated by a carrier, over a transmission medium. The “processor-readable or accessible medium” may include any medium that can store, transmit, or transfer information. Examples of accessible media include an electronic circuit, a semiconductor memory device, a read only memory (ROM), a flash memory, an erasable ROM (EROM), a floppy diskette, a compact disk (CD-ROM), an optical disk, a hard disk, a fiber optic medium, a radio frequency (RF) link, etc. The code segments may be downloaded via computer networks such as the Internet, Intranet, etc. The processor-readable or accessible medium may include data that, when accessed by a processor or circuitry, causes the processor or circuitry to perform the operations described herein. The term “data” herein refers to any type of information that is encoded for machine-readable purposes. Therefore, it may include programs, code, data, files, etc.

In one embodiment, a self-heating disk drive is disclosed that may utilize the components of the disk drive100discussed with reference toFIGS. 1 and 2. The self-heating disk drive100may include a voice coil motor (VCM), a spindle motor113, and a temperature sensor181. The VCM may include a VCM coil150, in which the VCM is configured to move an actuator130having heads64attached to distal ends of actuator arms160. The spindle motor113may include a plurality of spindle coils configured to spin disks46. Particularly, in one embodiment, the spindle motor113may be a three-phase spindle motor having three coil windings, as are well known in the art.

In one embodiment, temperature sensor181may be mounted to the flex circuit cable of the flex circuit cable assembly180. Alternatively, as is well known, the pre-amplifier42may be utilized to estimate an internal temperature of the disk drive based upon breakthrough voltage measurements of the preamplifier. Of course, it should be appreciated that the temperature sensor may be located at various locations within the disk drive to measure an internal temperature of the disk drive dependent upon design considerations. For example, as previously discussed, the temperature sensor may also be located on the PCBA114facing the HDA144.

Self-heating disk drive100preferably includes circuitry configured to command the application of current to the VCM coil150without loading the heads onto the disks46and to the spindle coils of the spindle motor113in a manner so as not to spin the disks46.

For example, current may be applied to the VCM coil150in an opposite direction to a typical loading current, such that the actuator assembly130and heads64are continuously forced towards a parked position against a stop away from the outer diameter of the disks, such that the actuator assembly130does not pivot. Alternatively, actuator assembly130may be continuously forced towards the landing zones of the inner diameter of the disks46adjacent the spindle48via current applied to the VCM coil150. In another embodiment, a latch mechanism may be utilized with the actuator assembly130. The latch mechanism may latch the actuator assembly130in the parked position such that the actuator assembly130is not allowed to pivot—in opposition to movement induced by current applied to the VCM coil150. After self-heating, the latch mechanism may un-latch allowing actuator assembly130to pivot such that heads64may be loaded onto disks46, respectively. In effect, VCM coil150having current pumped therethrough acts as a heater to heat up the internal components of the disk drive.

Similarly, current is applied to the spindle coils of the spindle motor in a manner so as not to spin the disks46. For example, in a three-phase spindle motor having three spindle coils, current may be applied to the three spindle coils in a switched-phase manner, thereby causing spindle currents to flow through the spindle coils, while not allowing the spindle motor to spin-up and spin the disks46. Alternatively, current may only be applied to a single coil or to a pair of coils of the three spindle coils in a manner so as not to spin the disks46.

In effect, both the VCM coil150and the spindle coils of the spindle motor113have current pumped therethrough and act as heaters to heat up the internal components of the disk drive.

The self-heating disk drive100may further utilize circuitry configured to determine if an internal temperature reading from temperature sensor181has reached a pre-determined spindle temperature, and if so, the circuitry is configured to apply current to the spindle coils of the spindle motor113in a normal manner, in order to allow the spindle motor113to spin-up the disks46. The circuitry is further configured to continuously monitor the internal temperature reading of the disk drive from the temperature sensor181.

Also, in one embodiment, the circuitry may be configured to: command the application of current to the spindle coils of the spindle motor113in a first out-of-phase manner such that the spindle motor113generates excess heat in spinning the disks46; and, if the internal temperature as monitored by the temperature sensor181reaches a pre-determined temperature, command the application of current to the spindle coils of the spindle motor113in a more power-efficient manner than the first out-of-phase manner.

For example, applying current to the spindle coils of the spindle motor113in a more power-efficient manner than the first out-of-phase manner, may be accomplished by applying current to the spindle coils of the spindle motor113in an in-phase manner such that spindle motor113does not generate excess heat in spinning the disks46. Alternatively, the more power-efficient manner may be less out-of-phase, but not completely in-phase, thereby generating less overall heat, but sufficient enough heat to keep the drive warm in a very cold environment. Additionally, the current applied to the spindle coils of the spindle motor113in the first out-of-phase manner may be utilized to spin the disk at a higher than normal spin speed to increase air-flow and heat distribution throughout the interior of the disk drive.

It should be understood that the pre-determined spindle temperature obtained from the temperature sensor181may be correlated to, but may not match, a temperature of the spindle motor at which the spindle motor can be spun-up. For example, if the temperature sensor181is located far from the spindle motor113, then the temperature reading obtained at the temperature sensor181may greatly diverge from the actual temperature of the spindle motor113. However, in a preferred embodiment, a calibration will be used such that the actual temperature at which the spindle motor113should be spun-up is correlated with the pre-determined spindle temperature that can be obtained at the temperature sensor181at the same moment. Similar analyses may be used with other predetermined temperature settings used to enable various levels of functionality of the disk drive.

It should be appreciated that, in one embodiment, the circuitry configured to accomplish this functionality may be microprocessor84. Microprocessor84may operate under the control of self-heating control code107stored in non-volatile memory106to execute the methods or processes in accordance with the embodiments of the present invention related to self-heating. For example, self-heating control code107may be implemented in software or firmware stored in non-volatile memory106or other locations and may be implemented by microprocessor84alone or in conjunction with other circuitry. Therefore, reference will be made hereinafter to microprocessor84as being the circuitry that implements this functionality.

However, it should be appreciated that a wide variety of other circuitry may be utilized instead of, or in addition to, microprocessor84, such as: a state machine, an application specific integrated circuit (ASIC), a central processing unit (CPU), a logic circuit, a controller, a micro-controller, or any type of circuitry capable of processing data.

Once the internal temperature reading of the disk drive reaches a pre-determined VCM temperature, microprocessor84may be configured to allow the VCM to load the heads64of the actuator assembly130onto respective disks46by commanding the application of current to the VCM coil150in the normal direction for head loading or releasing the latching mechanism. Further, if the internal temperature reading reaches a pre-determined read temperature, microprocessor84may be further configured to enable read operations through read/write channel68.

However, if the pre-determined read temperature is not reached, microprocessor84may be configured to allow current to the VCM coil150of the VCM to simply enable movement of the actuator arms160of the actuator assembly130without enabling reading or writing functionality of the read/write heads. For example, full-stroke movement, one-third stroke movement, or one-half stroke movement of the actuator arms160across the disks46may be enabled. This may increase air-flow movement within the disk drive enclosure and improve heating of the internal components of the disk drive. It has been found that in some drives one-third stroke movements generate the most heat from VCM coil150.

Alternatively, microprocessor84may enable read operations without determining whether the internal temperature reading has reached the pre-determined read temperature. When the internal temperature reading of the disk drive as read by temperature sensor181reaches a pre-determined write temperature, microprocessor84may further enable write operations through the read/write channel68.

It should be appreciated that current may be applied to the VCM coil150and to the spindle coils of the spindle motor113for variable periods of time. These variable time periods are dependent upon the amount of heating required to enable the internal disk drive temperature to reach the pre-determined temperatures associated with the previously-described stages of disk drive functionality, such as: loading the heads onto the disks, performing read operations, performing write operations, etc.

In this way, these various stages of operation can be reached in a power-efficient manner. This is especially important in mobile devices, wherein power is often derived from a battery source, and, therefore, there is a limited amount of power available from the battery. Moreover, since the internal temperature reading is continuously monitored, if an internal disk drive temperature becomes too cold again, for example, during a sleep or idle phase, the previously-described process will automatically enable self-heating.

It is noted that one embodiment of the invention may be described as a process, which is usually depicted as a flow chart, a flow diagram, a structure diagram, or a block diagram. Although a flow chart may describe the operations of the sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operation may be re-arranged. A process may correspond to a method, a function, a procedure, a subroutine, a subprogram, etc. When a process corresponds to a function, its termination corresponds to a return of the function to the calling function or the name function.

With reference toFIGS. 3A and 3B, flow diagrams are shown, illustrating a process for self-heating a disk drive according to one embodiment of the present invention. As previously described, many of the illustrated functions may be implemented under the control of microprocessor84and/or by other types of circuitry.

Referring now toFIG. 3A, a process300to self-heat a disk drive is described. It should be noted that an internal temperature of the disk drive is continuously monitored at block302utilizing a temperature sensor, such as temperature sensor181of the flex circuit cable assembly or a temperature sensor on the PCBA, previously discussed, and the internal temperature reading is continually utilized during the self-heating process300. As shown inFIGS. 3A and 3B, the internal temperature is continually read at different stages of process300(e.g. at process blocks304,312,320,328and336) from monitoring block302.

To begin with, at block304, an internal temperature value of the disk drive (TIDD) is read. For example, this may occur at power-on or after a sleep or idle phase. Based on the monitored TIDD, it is determined at decision block306whether TIDDis greater than a pre-determined spindle temperature value (TSPIN). TSPINdenotes a pre-determined temperature value, at which it has been determined that it is safe to spin-up the spindle motor. For example, in some disk drives to be utilized with mobile devices, it has been determined that when temperatures are below 5° C. the spindle motor113and other disk drive components do not operate properly and, in fact, may be damaged in operation. So, TSPINmay be set to 5° C. or, as discussed above, to a temperature reading indicative of 5° C. at the spindle. If TIDDis above TSPIN, then at block308the spindle motor113may be safely spun-up, and the self-heating disk drive process300moves to Circle A309, as will be discussed later.

However, if the TIDDis less than TSPIN, then the self-heating disk drive process300moves to block310. At block310, current is applied to both the VCM coil150and the spindle coils of spindle motor113. As previously discussed, in one example, current may be applied to the VCM coil150in an opposite direction to a loading current for loading the head onto the disk, such that actuator arms160and respective heads64are forced further towards their parked position against a stop. The actuator arms do not move, and the VCM coil150to which electrical current is being applied provides heat to the disk drive. Further, as previously described, in one example, current may be applied to the spindle coils of the spindle motor113in a switched-phase manner so as not to spin the disk, and the spindle coils may instead simply provide heat to the disk drive.

At block312TIDDis read, and at decision block314, TIDDis checked again to determine if it is greater than TSPIN. If not, disk drive self-heating process300returns to block310, wherein current continues to be applied to the VCM coil and spindle coils, as previously described.

However, if TIDDis greater than TSPIN, then at block308the spindle motor113of the disk drive is spun-up, such that disks46begin to rotate and process300moves to Circle A309.

At this point, the internal temperature of the disk drive (TIDD) is such that it is at least safe to spin-up the spindle motor113. This further increases the overall internal temperature of the disk drive because the spinning disks46induce air-flow within the disk drive providing for greater heat distribution.

At block320, the internal temperature value of the disk drive (TIDD) is read, and at decision block322it is determined whether TIDDis greater than a pre-determined VCM temperature value (TVCM). If not, at block324, current continues to be applied to the VCM coil150, and the spindle coils of the spindle motor113continue to spin the disks.

However, if TIDDis greater than TVCM, then heads46are loaded onto disks46at block326. The TVCMvalue is a temperature at which it is judged safe to load the heads onto the disks. For example, this temperature may be slightly above 5° C. dependent upon disk drive characterization. At this point, a normal loading current can be applied to the VCM coil150of the VCM in order to load the heads64of the actuator assembly130onto the disks46, respectively.

At block328, again the internal temperature value of the disk drive (TIDD) is read. At decision block330it is determined whether TIDDis greater than a pre-determined read temperature (TREAD), which is a predetermined temperature suitable for read operations. For example, a suitable read operation may be slightly less than 10° C. If TIDDis not greater than the TREAD, then at block322current is applied to the VCM coil150to enable actuator assembly movement and to the spindle coils of the spindle motor to continue spinning the disks46, and the internal disk drive heating process300moves back to block328.

Particularly, current may be applied to the VCM coil150to enable movement of the actuator arms160(as in normal operations) but without reading or writing with the heads64. More particularly, full-stroke movement, one-half stroke movement, or one-third stroke movement of the actuator arms160across the disks46may be enabled. By doing this, the VCM coil150further generates heat, and the movement of the actuator arms stimulates air-flow internally throughout the disk drive to improve heat distribution and self-heating. It has been found that one-third stroke movement generates the most heat from VCM coil150, whereas the one-half stroke movements and full stroke movements generate more air-flow within the disk drive.

If TIDDis greater than TREAD, then read operations can be begun for the disk drive. At block336, the internal temperature value of the disk drive (TIDD) is read. Then, at decision block340it is determined whether TIDDis greater than a predetermined write temperature (TWRITE). The pre-determined write temperature value TWRITEis a temperature that has been determined to be a suitable temperature at which write operations may be performed by the heads64with minimal errors. For example, it has been found in some disk drives that at temperatures slightly above 10° C. write operations can be performed with minimal errors.

If TIDDis not greater than TWRITE, then current to the VCM coil and spindle motor is applied as needed for read operations, and process300moves back to block336(block342). It should be appreciated that during this self-heating process300, prior to the enablement of the write operation, that microprocessor84of the disk drive may command the storing of write data received from the host36in disk drive memory (e.g., in buffer memory82) until a sufficient internal temperature of the disk drive is reached (e.g., TWRITE), such that write operations can begin and data from the host can be written to the disks46.

If TIDDis greater than TWRITE, then write operations may be performed, and at this point, the disk drive is fully functional (block344). Self-heating disk drive process300may be continuously run during disk drive operation.

Looking back to process block308, at which point the spindle motor113is spun-up, in one embodiment, current may be applied to the spindle coils of the spindle motor113in a first out-of-phase manner such that the spindle motor113generates excess heat in spinning-up the disks46and thereafter maintaining the disk46at a normal spin speed. For example, current may be applied to the spindle coils of the spindle motor 25° out-of-phase.

By doing this, the spindle motor113is run in an inefficient manner by utilizing an excessive amount of out-of-phase current applied to the spindle coils to ramp the disks46up to a normal spin speed and to maintain the disks at a normal spin speed. This results in the excessive heating of the spindle coils. This additional heating of the spindle coils aids in the self-heating process by raising the internal disk drive temperature (TIDD) at a faster rate.

Additionally, the current applied to the spindle coils of the spindle motor113in the first out-of-phase manner may also be utilized to spin the disks46at higher than normal spin speeds to increase air-flow and heat distribution throughout the interior of the disk drive.

For example, current may be applied to the spindle coils of the spindle motor113in an out-of-phase manner at a normal speed (e.g., at 5,400 RPM) such that spindle motor113generates excess heat in spinning the disks46. Also, current may be applied to the spindle coils of the spindle motor113in an out-of-phase manner to spin the disks46, but at higher than normal spin speeds (e.g., at twice the normal speed—10,800 RPM) to increase air-flow and heat distribution throughout the interior of the disk drive. Utilizing higher than normal spin speeds preferably occurs prior to loading the heads64onto the disks46, but in some embodiments, higher than normal spin speeds may be used after head loading.

When the internal temperature as monitored by the temperature sensor181reaches a pre-determined temperature, current may be applied to the spindle coils of the spindle motor113in a more power-efficient manner than the previously described first out-of-phase manner. For example, applying current to the spindle coils of the spindle motor113in a more power-efficient manner than the first out-of-phase manner may be accomplished by applying current to the spindle coils of the spindle motor113in an in-phase manner such that spindle motor113does not generate excess heat in spinning the disks46.

However, the more power-efficient manner may also be simply less out-of-phase, but not completely in-phase, thereby generating some additional excess heat in order to maintain sufficient heat generation to keep the drive warm in a very cold environment.

It should be appreciated that the rest of the self-heating process300after process block308remains the same, as previously described, except that current is being applied to the spindle coils of the spindle motor113in an out-of-phase manner such that the spindle motor113generates excess heat in spinning the disks46.

However, at a certain point, as previously discussed, when the internal disk drive temperature reading (TIDD) reaches a pre-determined temperature (e.g., a normal spindle operation temperature), the application of current to the spindle coils of the spindle motor113may be suitably switched to a more power-efficient manner.

Particularly, in one example, after the internal temperature disk drive temperature reading (TIDD) reaches TWRITE, such that the disk drive is fully operational, the application of current to the spindle coils may be suitably switched such that current is applied in a more a power-efficient manner than the first out-of-phase manner (e.g. in an in-phase or only slightly out-of-phase manner), such that the spindle motor113does not generate as much excess heat in spinning the disks46, as previously discussed.

In this way, after the disk drive has been self-heated in a rapid fashion by running the spindle motor113out-of-phase to generate excess heat, the disk drive may thereafter be run in a more efficient manner to conserve power. This may be important in disk drives utilized in mobile devices that rely on battery power.

As described above, self-heating disk drive process300continuously monitors the internal temperature of the disk drive at the various stages of disk drive functionality. Thus, current is applied to the spindle coils of the spindle motor and to the VCM coil for variable periods of time at different stages of the disk drive self-heating process.

By continuously monitoring the internal disk drive temperature, and applying current to the VCM coil and the spindle coils of the spindle motors for variable periods of time to enable successive stages of functionality (e.g., spinning up, loading, reading, and writing), the disk drive self-heats in an efficient and rapid fashion. This is especially important when the disk drive is utilized with mobile devices (e.g. personal digital assistants, cell-phones, cameras, etc.) in which power conservation to maximize battery power is important.

Further, since the various previously-described temperature values for each of the various stages are continuously monitored for, if the disk drive becomes cold again, for example, during a sleep or idle phase, the previously-described process will automatically enable self-heating.

Although only shown at particular points within process300, the circuitry preferably continuously compares the internal temperature reading with all of the pre-determined temperature values. Thus, if the internal temperature reading falls below a previously surpassed value, the disk drive may return to a more intensive heating process, or may return an error to the user. In one embodiment, the disk drive may indicate to the user that it is too cold to use the drive.

It should be appreciated by those with skill in this art that, although embodiments of the invention have been previously described with reference to particular disk drive components, the embodiments of the invention may be utilized in a wide variety of differing types of storage devices having rotatable media, and that the details disclosed in describing the embodiments of the invention are not intended to limit the scope of the invention as set forth in the appended claims. It should be further understood that various steps shown inFIGS. 3A–3Bmay be changed or omitted, while performing different embodiments of the invention.