Data storage device that independently drives external and internal fine-tuning actuators

Abstract

The present invention discloses a data storage device, which includes a plurality of disks, each disk including a top disk surface and a bottom disk surface. A plurality of internal actuator arms each include a first internal fine-tuning actuator configured to actuate a top head above one of the top disk surfaces and a second internal fine-tuning actuator configured to actuate a bottom head above one of the bottom disk surfaces. A first external actuator arm includes a first external fine-tuning actuator configured to actuate the top head above the top disk surface of the top disk, and a second external actuator arm includes a second external fine-tuning actuator configured to actuate the bottom head above the bottom disk surface of the bottom disk, wherein the internal fine-tuning actuator is controlled independently of the external fine-tuning actuator.

Description

Background Art

[0001] A data storage device such as a disk drive includes a disk and a head connected to the distal end of an actuator arm that is pivoted by a voice coil motor (VCM) to position the head radially over the disk. The disk includes a plurality of radially spaced concentric tracks for recording user data sectors and servo sectors. The servo sectors include head positioning information (e.g., track addresses) that is read by the head and processed by a servo control system to control the actuator arm as it seeks from track to track.

[0002] Figure 1 A prior art disk format 2 is shown which includes servo sectors 60-6 recorded around the circumference of each servo track. N A plurality of servo tracks 4 are defined. Each servo sector 6 i The servo sector 6 includes a preamble 8 for storing a periodic pattern (which allows proper gain adjustment and timing synchronization of the read signal) and a synchronization mark 10 for storing a special pattern for symbol synchronization to a servo data field 12. The servo data field 12 stores coarse head positioning information, such as a servo track address, used to position the head over a target data track during a seek operation. Each servo sector 6 i Also included are servo burst groups 14 (e.g., N servo bursts and Q servo bursts) that are recorded with predetermined phases relative to each other and relative to the servo track centerline. The phase-based servo bursts 14 provide fine head position information for centerline tracking while accessing data tracks during write / read operations. A position error signal (PES) is generated by reading the servo bursts 14, where the PES represents the measured position of the head relative to the centerline of the target servo track. The servo controller processes the PES to generate a control signal applied to a head actuator (e.g., a voice coil motor) to actuate the head radially over the disk in a direction that reduces the PES. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] Figure 1 A prior art disk format is shown which includes a plurality of servo tracks defined by servo sectors.

[0004] Figure 2A A data storage device in the form of a disk drive according to an embodiment is shown, the data storage device comprising a plurality of disks, each disk comprising a top disk surface and a bottom disk surface.

[0005] Figure 2BAn embodiment is shown in which a plurality of inner actuator arms each include a first inner fine-tuning actuator configured to actuate a top head above one of the top disk surfaces and a second inner fine-tuning actuator configured to actuate a bottom head above one of the bottom disk surfaces, and a top outer actuator arm and a bottom outer actuator arm each include an outer fine-tuning actuator configured to actuate the top head above the top disk surface of the outer top disk and to actuate the bottom head above the bottom disk surface of the outer bottom disk.

[0006] Figure 2C An embodiment is shown in which the fine-tuning actuator for the top head is mechanically identical to the fine-tuning actuator for the bottom head due to their flipped orientation relative to the top and bottom disk surfaces, resulting in opposite radial movements in response to a common control signal.

[0007] Figure 3 An embodiment is shown in which a fine-tuning drive generates a control signal that is simultaneously applied to the fine-tuning actuator of either the inner actuator arm or the outer actuator arm.

[0008] Figure 4 A control circuit for a fine-tuning actuator applying a control signal to either an internal actuator arm or an external actuator arm according to an embodiment is shown.

[0009] Figure 5A An embodiment is shown in which a first fine-adjustment drive controls the fine-adjustment actuator of the inner actuator arm and a second fine-adjustment drive simultaneously controls the fine-adjustment actuator of the outer actuator arm.

[0010] Figure 5B An embodiment is shown in which the control signals generated by the fine tuning actuators can be inverted to actuate the fine tuning actuators of the top disk surface and the bottom disk surface simultaneously. DETAILED DESCRIPTION

[0011] Figure 2A and Figure 2B A data storage device in the form of a disk drive according to an embodiment is shown, the data storage device comprising a plurality of disks 161-16 N , each disk includes a top disk surface and a bottom disk surface. A plurality of internal actuator arms 181-18 NEach includes a first internal fine adjustment actuator (e.g., 201) and a second internal fine adjustment actuator (e.g., 202), the first internal fine adjustment actuator being configured to actuate a top head (e.g., 221) above one of the top disk surfaces, and the second internal fine adjustment actuator being configured to actuate a bottom head (e.g., 222) above one of the bottom disk surfaces. The first external actuator arm 241 includes a first external fine adjustment actuator 261, the first external fine adjustment actuator being configured to actuate the top head above the top disk surface of the top disk, and the second external actuator arm 242 includes a second external fine adjustment actuator 262, the second external fine adjustment actuator being configured to actuate the bottom head above the bottom disk surface of the bottom disk. The coarse adjustment actuator (e.g., VCM 28) is configured to simultaneously move the actuator arms to actuate the heads above their respective disk surfaces, wherein the internal fine adjustment actuators are controlled independently of the external fine adjustment actuators.

[0012] exist Figure 2A In an embodiment of the present invention, the disk drive includes a control circuit 30 configured to process a read signal 32 from the head to demodulate the servo sector and generate a position error signal (PES) representing the error between the actual position of the head and a target position relative to a target data track. A servo control system in the control circuit 30 filters the PES using a suitable compensation filter to generate a control signal 34 that is applied to the VCM 28, which rotates the actuator arm about a pivot to actuate the head radially over the disk in a direction that reduces the PES. The head is also servoed using a fine-tuning actuator, such as a piezoelectric (PZT) actuator, which is configured to actuate the suspension relative to the actuator arm, such as a PZT actuator. Figure 2B , and / or configured to actuate the head relative to the suspension. The servo sectors may include any suitable head position information, such as track addresses for coarse positioning and servo pulses for fine positioning. In one embodiment, the servo pulses may include any suitable pattern, wherein at least one servo pulse consists of a periodic sequence of magnetic transitions, such as an amplitude-based servo pattern or a phase-based servo pattern ( Figure 1 ).

[0013] Figure 2C An embodiment of a fine-tuning actuator including a PZT element configured to actuate a suspension relative to an actuator arm is shown. In this embodiment, the fine-tuning actuator for the top head (e.g., inner fine-tuning actuator 201) is mechanically identical to the fine-tuning actuator for the bottom head (e.g., inner fine-tuning actuator 202). In this embodiment, the bottom fine-tuning actuator and suspension are "flipped" relative to the top fine-tuning actuator and suspension, as shown in FIG. Figure 2CAs shown, when the control signal is applied to both the top fine-tune actuator / bottom fine-tune actuator of the inner actuator arm simultaneously, it causes opposite radial movement of the top fine-tune actuator / bottom fine-tune actuator. In one embodiment, simultaneously actuating the top fine-tune actuator / bottom fine-tune actuator of the inner actuator arm in opposite radial directions damps the vibration mode of the actuator arm.

[0014] Figure 3 shows a control circuit according to an embodiment in which all fine actuators are mechanically identical and the fine actuators of the bottom head are flipped relative to the fine actuators of the top head, such as Figure 2C As shown. Fine-tuning driver 36 generates control signal 38, which is selectively applied (via demultiplexer 40) to the internal fine-tuning actuators (e.g., 201 and 202) of the internal actuator arms or to the external fine-tuning actuators (261 and 262) of the external actuator arms. Therefore, in this embodiment, demultiplexer 40 can be configured so that control signal 38 drives all internal fine-tuning actuators simultaneously, including driving the top fine-tuning actuator / bottom fine-tuning actuator in opposite radial directions, so as to attenuate the vibration mode of the actuator arm. Alternatively, the demultiplexer can be configured so that control signal 38 drives the external fine-tuning actuators simultaneously (in this embodiment, the top fine-tuning actuator is driven in the opposite radial direction from the bottom fine-tuning actuator). In this embodiment, driving the internal fine-tuning actuators simultaneously without driving the external fine-tuning actuators can attenuate disturbances that may otherwise affect the internal actuator arms. Similarly, simultaneously driving the outer fine actuator without driving the inner fine actuator can attenuate disturbances that might otherwise affect the outer actuator arm.

[0015] Figure 4 According to an embodiment, a method for Figure 3 A control circuit for a fine-tuning actuator in which a control signal 38 is applied to either the internal actuator arm or the external actuator arm. The control circuit includes an input stage including a digital-to-analog converter 42 for converting a digital control signal into an analog control signal 38, and a differential amplifier 44 for amplifying the analog control signal 38. Switches 461 and 462 are configured to select an external fine-tuning actuator or an internal fine-tuning actuator to be driven by the input stage. Switch 48 is configured to apply feedback from the external fine-tuning actuator or the internal fine-tuning actuator drive stage (depending on which is active) to the differential amplifier 44. When the internal fine-tuning actuator or the external fine-tuning actuator is not selected (inactive), the corresponding switches 461 and 462 are configured so that the corresponding output stage is biased to an output common mode. Figure 4 In the example of , the switches are configured such that the internal trim actuator is active (driven by control signal 38) and the external trim actuator is inactive (the output stage is biased to output common mode).

[0016] Figure 5A A control circuit according to an embodiment is shown, wherein a first fine tuning driver 361 generates a first control signal 381 for controlling an inner fine tuning actuator (e.g., 201 and 202), and a second fine tuning driver 362 generates a second control signal 382 for independently controlling outer fine tuning actuators 261 and 262. In one embodiment, the inner fine tuning actuator and the outer fine tuning actuator may be controlled simultaneously to access two disk surfaces simultaneously. For example, a top head may access a top disk surface of a top disk while one of the middle heads simultaneously accesses one of the middle disk surfaces (top or bottom) of a middle disk. Figure 5A In an embodiment of the present invention, the fine-tuning actuators are mechanically identical, wherein the bottom fine-tuning actuator is "flipped" relative to the top fine-tuning actuator, such as Figure 2C As shown, a common control signal 381 drives all internal fine-tuning actuators, and a common control signal 382 drives two external fine-tuning actuators.

[0017] exist Figure 5B In the alternative embodiment shown, the top fine-tuning actuator and the bottom fine-tuning actuator are configured to actuate in the same radial direction in response to a common control signal. Thus, in this embodiment, the first fine-tuning driver 361 generates a first control signal 501 for controlling the top inner fine-tuning actuator of the middle disk, and a second control signal 502 of opposite polarity (via inverter 52) for controlling the bottom inner fine-tuning actuator of the middle disk. Similarly, the second fine-tuning driver generates a first control signal 541 for controlling the top outer fine-tuning actuator of the top disk, and a second control signal 542 of opposite polarity (via inverter 56) for controlling the bottom outer fine-tuning actuator of the bottom disk. In this embodiment, the negative polarity control signals 502 and 542 are shown as being generated by inverting the corresponding positive polarity control signals 501 and 541. However, Figure 5B The analog inverters shown are merely indicative that in one embodiment, the control signals generated by each fine-tuning actuator have opposite polarities. In other embodiments, the positive polarity control signals / negative polarity control signals may be generated in any other suitable manner, such as by using a non-inverting amplifier and an inverting amplifier with equal gain. Furthermore, if the fine-tuning actuators are configured to actuate in the same radial direction in response to a common control signal, then the control signals may be generated in the other embodiments described above (such as in Figure 3 A similar technique of inverting the control signals for the top fine-tuning actuator / bottom fine-tuning actuator is implemented in an embodiment of the present invention.

[0018] Any suitable control circuit can be used to implement the flowcharts in the above embodiments, such as any suitable integrated circuit or circuit. For example, the control circuit can be implemented in a read channel integrated circuit, or in a component separate from the read channel, such as a data storage controller, or some of the above operations can be performed by the read channel, while other operations can be performed by the data storage controller. In one embodiment, the read channel and the data storage controller are implemented as separate integrated circuits, and in alternative embodiments, they are manufactured as a single integrated circuit or system on chip (SOC). In addition, the control circuit may include a suitable power supply circuit and / or a suitable preamplifier circuit, which is implemented as a separate integrated circuit, integrated into the read channel or data storage controller circuit, or integrated into the SOC.

[0019] In one embodiment, the control circuit includes a microprocessor that executes instructions, and the instructions are operable to make the microprocessor perform the flow chart described herein. The instructions can be stored in any computer readable medium. In one embodiment, they can be stored in a non-volatile semiconductor memory external to the microprocessor or integrated with the microprocessor in the SOC. In another embodiment, the control circuit includes a suitable logic circuit, such as a state machine circuit. In some embodiments, at least some of the flow chart blocks can be implemented using analog circuits (e.g., analog comparators, timers, etc.), and in other embodiments, some of the blocks can be implemented using digital circuits or a combination of analog / digital circuits.

[0020] Furthermore, any suitable electronic device, such as a computing device, a data server device, a media content storage device, etc., may include the storage medium and / or control circuitry described above.

[0021] The various features and processes described above can be used independently of each other, or can be combined in various ways. All possible combinations and sub-combinations are intended to fall within the scope of the present disclosure. In addition, certain methods, events or process blocks can be omitted in some specific implementations. The methods and processes described herein are also not limited to any specific sequence, and the blocks or states associated therewith can be performed in other appropriate sequences. For example, the tasks or events described can be performed in a sequence different from that specifically disclosed, or multiple can be combined in a single block or state. Exemplary tasks or events can be performed serially, in parallel or in some other way. Tasks or events can be added to or deleted from the disclosed exemplary embodiments. The exemplary systems and components described herein can be configured differently from those described. For example, compared to the disclosed exemplary embodiments, elements can be added, removed or rearranged.

[0022] Although certain example embodiments have been described, these embodiments are presented only as examples and are not intended to limit the scope of the invention disclosed herein. Therefore, nothing in the above description is intended to imply that any particular feature, characteristic, step, module, or block is necessary or indispensable. In fact, the novel methods and systems described herein can be embodied in various other forms. In addition, various omissions, substitutions, and changes in the form of the methods and systems described herein can be made without departing from the essence of the embodiments disclosed herein.

Claims

1. A data storage device comprising: a plurality of disks, each disk comprising a top disk surface and a bottom disk surface; a plurality of internal actuator arms, each internal actuator arm comprising a first internal fine-tune actuator configured to actuate a top head over one of the top disk surfaces and a second internal fine-tune actuator configured to actuate a bottom head over one of the bottom disk surfaces; a first external actuator arm including a first external fine-tuning actuator configured to actuate a top head above a top disk surface of a top disk; a second external actuator arm, the second external actuator arm comprising a second external fine adjustment actuator configured to actuate the bottom head above a bottom disk surface of the bottom disk; as well as a control circuit configured to control the first internal fine-tuning actuator of each of the plurality of internal actuator arms to actuate the top head of the corresponding internal actuator arm along a first radial direction, and simultaneously control the second internal fine-tuning actuator of each of the plurality of internal actuator arms to actuate the bottom head of the corresponding internal actuator arm along a second radial direction opposite to the first radial direction.

2. The data storage device according to claim 1, wherein: The first internal fine-tune actuator has a first electrical orientation and the second internal fine-tune actuator has a second electrical orientation flipped relative to the first electrical orientation; as well as The control circuit is further configured to control the first internal fine-tuning actuator to actuate the top head of the corresponding internal actuator arm along the first radial direction, and to control the second internal fine-tuning actuator to actuate the bottom head of the corresponding internal actuator arm along the second radial direction opposite to the first radial direction, by simultaneously applying control signals to the first internal fine-tuning actuator and the second internal fine-tuning actuator of the corresponding internal actuator arm.

3. The data storage device according to claim 1, wherein: the first external fine-adjustment actuator of the first external actuator arm having a first electrical orientation and the second external fine-adjustment actuator of the second external actuator arm having a second electrical orientation flipped relative to the first electrical orientation; as well as The control circuit is further configured to control the first external fine adjustment actuator of the first external actuator arm to actuate the top head of the first external actuator arm along the first radial direction, and simultaneously control the second external fine adjustment actuator of the second external actuator arm to actuate the bottom head of the second external actuator arm along the second radial direction opposite to the first radial direction, by simultaneously applying control signals to the first external fine adjustment actuator of the first external actuator arm and the second external fine adjustment actuator of the second external actuator arm.

4. The data storage device according to claim 1, wherein the control circuit is further configured to: controlling the first inner fine actuator based on first servo data read from a corresponding top disk surface to access the top disk surface using a corresponding top head of the corresponding inner actuator arm; and The first external fine actuators of the first external actuator arms are simultaneously controlled based on second servo data read from the corresponding top disk surfaces to simultaneously access the top disk surfaces using corresponding top heads of the first external actuator arms.

5. The data storage device according to claim 1, wherein the control circuit is further configured to: generating a control signal; and The control signal is selectively applied to at least one of the internal fine-tuning actuators or to at least one of the external fine-tuning actuators.

6. The data storage device according to claim 5, wherein the control circuit is further configured to: The control signal is selectively applied to at least two of the internal fine-tuning actuators or to both of the external fine-tuning actuators.

7. The data storage device of claim 1, further comprising a coarse actuator configured to simultaneously move the inner actuator arm and the outer actuator arm to actuate the head over a corresponding disk surface.

8. A control circuit, comprising: An instruction, which when executed is configured to initiate a control signal; a first switch switchable between a first active mode and a first inactive mode, wherein in the first active mode the first switch is configured to simultaneously apply the control signal to the internal fine-tuning actuators of the internal actuator arms to actuate the first internal fine-tuning actuator and the second internal fine-tuning actuator of each of the internal actuator arms in opposite radial directions; A second switch switchable between a second active mode and a second inactive mode, wherein in the second active mode the second switch is configured to apply the control signal to the external fine-tuning actuator of the external actuator arm, wherein each internal actuator arm and each external actuator arm includes a head configured to access a disk surface of the disk.

9. A control circuit, comprising: means for initiating a control signal, first means for switching between a first active mode and a first inactive mode, wherein in the first active mode the first means is configured to simultaneously apply the control signal to the internal fine-adjustment actuators of the internal actuator arms to actuate the first internal fine-adjustment actuator and the second internal fine-adjustment actuator of each of the internal actuator arms in opposite radial directions; A second device for switching between a second active mode and a second inactive mode, wherein in the second active mode the second device is configured to apply the control signal to the external fine-tuning actuator of the external actuator arm, wherein each internal actuator arm and each external actuator arm includes a head configured to access a disk surface of the disk.

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