Patent Application
20100309574
Data storage devices utilize ramp load/unload technology in order to prevent damage to the data storage medium. In a data storage device, read/write operations are performed by read/write heads, which are carried by one or more sliders. Each slider is engaged to an actuator arm.
During a ramp load operation, each actuator arm is moved such that it is supported by a surface of a support structure. In this manner, the sliders, and hence the read/write heads, are moved off of the data storage medium prior to power-down, for example, and safely positioned on the support structure. In some instances, an actuator arm may include a lift tab that rests directly on the support structure to hold the slider off the data storage medium. Generally, the support structure includes a shallow ramp on the side closest to the data storage medium. During a ramp unload operation, such as during a power-on sequence, the slider is unloaded by moving the slider off the ramp and over the surface of the data storage medium when the medium has reached the appropriate rotational speed.
In one example, the disclosure is directed to a method for detecting a ramp load/unload operation. The method comprises measuring a signal value generated by a transducer element during either a ramp unload operation or a ramp load operation in a data storage device, and analyzing the signal value to determine whether the ramp load operation or the ramp unload operation in the data storage device has occurred.
In another example, the disclosure is directed to a data storage device comprising a data storage medium, an actuator arm comprising a suspension, and a ramp component forming a surface. The data storage device further comprises a transducer element in mechanical communication with the suspension, and a processor in electrical communication with the transducer element. When the slider is unloaded and when the slider is loaded, the transducer element generates a signal. The processor analyzes the signal to determine whether the ramp load operation or the ramp unload operation in the data storage device has occurred.
In another example, the disclosure is directed to a computer-readable medium comprising instructions that cause a processor in electrical communication with a data storage device to measure a signal value generated by a transducer element during either a ramp unload operation or a ramp load operation in a data storage device, and analyze signal value to determine whether the ramp load operation or the ramp unload operation in the data storage device has occurred.
These and various other features and advantages will be apparent from a reading of the following detailed description.
In general, the disclosure describes techniques for detecting ramp contact during ramp load/unload operations of a data storage medium. A transducer signal generated during movement of a suspension may be measured and analyzed in order to determine whether a ramp load operation or a ramp unload operation has occurred. As an example, measurement circuitry may first measure the value of the electrical signal generated by a transducer element engaged to a suspension. Then, a processor may analyze the signal value to determine whether a ramp load/unload operation has occurred.
By using an electrical signal generated by a transducer engaged to the suspension of an actuator arm, the accuracy of ramp load/unload detection may be improved. In addition, detection of a ramp load/unload operation may be simplified by reducing the complexity in detection algorithms. Further, using an electrical signal generated by a transducer engaged to the suspension of an actuator arm to detect ramp load/unload operations may reduce dwell track locations because the ramp load/unload times are accurately known. The electrical signal generated by a transducer engaged to the suspension of an actuator arm during ramp load/unload operations may also be used to perform axial run-out checks. Further still, the electrical signal generated by a transducer engaged to the suspension of an actuator arm during ramp load/unload operations may be used to detect a ramp contact radius and thus mitigate potential head/media contact, media damage, and particle generation. Further still, the electrical signal generated by a transducer engaged to the suspension of an actuator arm during ramp load/unload operations may also be used to detect individual heads or head gimbal assembly contact.
Actuator assembly 106 is shown in two positions: A and B. As shown with position A, slider 112 is in an unloaded position, in which data storage device 100 may be performing a read or write operation. In contrast, position B shows slider 112 in a loaded position. For example, actuator assembly 106 may rotate slider 112 into a loaded position prior to a power-down of data storage device 100 or in response to a load command.
To reach a loaded position, voice coil 118 interacts with a permanent magnet (not shown) to rotate actuator assembly 106 off data storage medium 102. As actuator assembly 106 reaches the outer diameter of data storage medium 102, lift tab 116 interacts with ramp component 120. Specifically, after lift tab 116 contacts surface 122 of ramp component 120, further rotation of actuator assembly 106 causes lift tab to slide up surface 122 of ramp component 120. Actuator arm 108 flexes vertically, allowing the rotation and slider 112 to be lifted from data storage medium 102. The rate at which slider 112 is lifted from data storage medium 102 is dependent on the slope of surface 122 relative to the data storage plane of data storage medium 102. In some examples, the initial slope of surface 122 may be between five and thirty degrees. In other examples, the initial slope of surface 122 may be about sixteen degrees.
In the final loaded position B, lift tab 116 may rest in a detent at the top of surface 122. The detent in surface 122 may provide a semi-locked position for lift tab 116. This may secure actuator assembly 106 in position B even in the event of an external shock to data storage device 100.
In some examples, ramp component 120 forms groove 124 within surface 122. Groove 124 may reduce the contact area between lift tab 116 and ramp component 120. The reduced contact area between ramp component 120 and lift tab 116 provided by groove 124 may reduce the tangential frictional force from the interface of lift tab 116 and ramp component 120.
Load/unload ramp 120 is shown on the outer diameter of data storage medium 102. In other embodiments, load/unload ramp 120 may be located near the center of data storage medium 102. In either configuration, benefits of detecting ramp load/unload operations are present. As will be described in more detail below, in accordance with this disclosure, an electrical signal, e.g., a voltage, produced by a transducer element used as a microactuator in response to a ramp load/unload operation may be detected using the same electrical connection path used to power the microactuators to finely position the read/write elements during read and write operations.
Engaged to suspension 107 is slider 112. Slider 112 includes a read/write head (not shown) with read/write elements for reading data from and writing data to data storage medium 102. Transducer elements 132A and 132B (hereafter “transducer elements 132”) used as microactuators operate to flex load beam 128 in order to move the read/write head of slider 112 during read and write operations. Transducer elements 132 may be used to finely position the read/write elements of the read/write head relative to data tracks on a data storage disc (not shown). In one example, transducers 132A and 132B are connected in parallel and have one side grounded to suspension 107 via electrical interconnects 134A and 134B. Examples of transducers include piezoelectric elements (e.g., lead zirconate titanate (“PZT”)), capacitive devices, and electrostatic devices. Each of these example transducers may be configured to generate a signal upon micro displacement. In one specific example, the signals generated may be the back emf of the PZT transducer elements. Other example transducers not specifically mentioned in the disclosure are nevertheless considered to form part of the disclosure.
Transducer elements 132 may also be used to measure deflections in flexible load beam 128. Transducer elements 132 produce an electrical signal in response to a deflection, such as a deflection occurring when the read/write head contacts a data storage medium (not shown). The electrical signal may be detected using the same electrical connection path used to power transducer elements 132 to finely position the read/write elements. By measuring electrical signals from transducer elements 132, contact between the read/write head and a data storage medium can be reliably detected. Detecting such contact may be useful to determine when maintenance of a head merge station is required to prevent damage to data storage media during the head merge process, for example.
In accordance with this disclosure, an electrical signal produced by one of transducer elements 132A or 132B in response to a ramp load/unload operation may also be detected using the same electrical connection path used to power transducer elements 132 to finely position the read/write elements. As used in this disclosure, the term “ramp load operation” may refer to the initial contact between actuator arm 108/slider 112 and ramp 120. Or, the term “ramp load operation” may refer to the contact between actuator arm 108/slider 112 and ramp 120 as actuator arm 108 moves up ramp 120. Or, the term “ramp load operation” may refer to the initial contact between actuator arm 108/slider 112 and ramp 120, as well as the contact between actuator arm 108/slider 112 and ramp 120 as actuator arm 108 moves up ramp 120. Similarly, the term “ramp unload operation” may refer to the contact between actuator arm 108/slider 112 and ramp 120 as actuator arm 108 moves down ramp 120. Or, the term “ramp unload operation” may refer to the final contact between actuator arm 108/slider 112 and ramp 120 as actuator 108 moves completely off ramp 120. Or, the term “ramp load operation” may refer to the contact between actuator arm 108/slider 112 and ramp 120 as actuator arm 108 moves down ramp 120, as well as the final contact between actuator arm 108/slider 112 and ramp 120 as actuator 108 moves completely off ramp 120. By detecting the electrical signal produced by a transducer element 132 in response to a ramp load/unload operation, the accuracy of ramp load/unload detection may be improved and the complexity of detection algorithms may also be reduced.
It should be noted that although the disclosure describes examples in which the electrical signal generated by a transducer element 132 used as a microactuator is used to detect ramp load and ramp unload operations, other examples consistent with the disclosure may use a transducer for ramp load and ramp unload detection that is mechanically engaged to the suspension, actuator arm, or the like that performs no microactuation function whatsoever. That is, the transducer may be used for the sole purpose of detecting ramp load or unload operations.
Further, it should be noted that although the disclosure describes using a signal for detecting a ramp load or unload operation, there may be additional signals used. For example, in a data storage device that includes multiple data storage media and therefore multiple actuator arms, signals in addition to the signal generated by either transducer 132A or 132B may be used to detect ramp load and ramp unload operations.
Data storage device 100 includes one or more data storage media 102. Each data storage medium 102 includes one or more data storage surfaces (e.g., magnetically recordable data storage surfaces). Data storage device 100 also includes actuator assembly 106 and flex tape 136. Actuator assembly 106 includes actuator arm 108 having suspension 107 and one or more read/write heads for each of the data storage surfaces of media 102. The read/write heads each include one or more head positioning transducer elements or microactuators 132.
Contact detection circuit 160 optionally includes sense amplifier 162, which amplifies signals received from transducer elements 132. Contact detection circuit 160 also optionally includes band pass filter 164, which may isolate portions of output signals from one of transducer elements 132 that indicate ramp load/unload operation.
Contact detection circuit 160 includes measurement circuitry 166 that measures the value of the signal from transducer elements 132 received from signal path 150. Contact detection circuit further includes processor 168 that analyzes the value of the signal to determine whether a ramp load/unload operation has occurred. Processor 168 may also perform additional analysis on signal information, as well as executing instructions stored in memory 170 to log data to memory 170, as will be described in more detail below. Although memory 170 is shown in
By way of specific example, during a ramp load operation, a transducer element 132 may generate a signal, e.g., a voltage, during the initial contact between actuator arm 108 and ramp 120. The signal is conducted through flex tape 136 to contact detection circuit 160. Sense amplifier 162 may amplify the signal received via flex tape 136 and then forward the amplified signal to band pass filter 164, if present. Band pass filter 164 may isolate portions of the signal that indicate ramp load/unload operation. The signal is then forwarded to measurement circuitry 166. Measurement circuitry 166 measures the value of the signal generated by one of the two parallel connected transducer elements 132. Contact detection circuit includes processor 168 that analyzes the signal value to determine whether a ramp load/unload operation has occurred. Processor 168 may also perform additional analysis on signal information, as well as executing instructions stored in memory 170 to log data to memory 170. Although memory 170 is shown in
Processor 168 may analyze the signal value by comparing the value to a threshold value. For example, if data storage device 100 is performing a ramp load operation, and thus moving actuator arm 108 off of data storage medium 102 and onto ramp 120, the initial contact between actuator arm 108 and ramp 120 may cause one of transducer element 132A or transducer element 132B to generate a signal, e.g., a voltage. Then, processor 168 compares the value to a threshold value stored in a memory either located within processor 168, such as memory 170, or in electrical communication with processor 168. If the value exceeds the threshold value, then processor 168 determines that a ramp load or unload operation has begun.
In some examples, the threshold value may be a static value. That is, the stored threshold value may be constant over time. For example, the threshold value may be calculated and stored during manufacture of the data storage device and remain constant until manually reprogrammed, for example.
In other examples, the threshold value may be a dynamic value. That is, the stored value may automatically adjust over time. For example, the threshold value may be calculated and stored during manufacture of the data storage device, but the threshold value may be automatically adjusted over time to account for variations in the detected transducer element signals. For example, the threshold value may be determined and stored during manufacture of the data storage device. Then, processor 168 may be configured to execute instructions that result in data related to the signal, e.g., the signal generated by transducer element 132A, being stored to memory 170. Over time, the value of the signal generated by transducer element 132A or 132B may increase or decrease. Processor 168 may be configured to execute instructions that cause the dynamic threshold value to be automatically adjusted accordingly to account for the variation in the signal value. In this manner, the threshold value may be maintained at a certain level above an averaged detected signal value, thereby allowing swings in calibration of the data storage device.
In other examples, processor 168 may analyze the signal value over a period of time longer than that of spike 202. For example, processor 168 may analyze the signal value over a time period 206, as shown in
In another example, processor 168 may analyze the signal by performing a trend analysis to determine whether a ramp load (or unload) operation has occurred. Referring again to
It should be noted that any portion of time period 206 may be used in determining whether a ramp load operation has been completed. Although only the portion of time period 206 that includes the initial contact between the actuator arm and ramp (spike 202), and the entire time period 206 that includes both the initial contact between the actuator arm and the ramp, as well as the contact as the actuator arm moves up the ramp, have been described, any other portions of the time period 206 may be used to determine whether a ramp load operation has occurred. For example, a trend analysis may include only the portion of time period 206 that includes the contact of the actuator arm and the ramp as the arm moves up the ramp, excluding the initial contact.
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All of the techniques for detecting a ramp load operation described above in conjunction with the power off and load operation of
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In some examples, the threshold value may be either a predetermined static value or a dynamic value.
In other examples, analyzing the signal value may include comparing the signal value to previously stored data, wherein the previously stored data is representative of a trend of signal values over, and determining whether the ramp load operation or the ramp unload operation in the data storage device has occurred based upon the comparison.
In some examples, the transducer element may be selected from a group consisting of a piezoelectric element, a capacitive element, and an electrostatic element.
In other examples, the signal value may comprise a first value indicating at least one of an initial ramp contact and a final ramp contact, and a second value indicating movement along the ramp.
The techniques described in this disclosure may, in some cases, improve the detection accuracy of ramp load and unload operations. For example, PZT voltage gain is very high, resulting in a high signal to noise ratio that may improve accuracy in detection. The techniques described in this disclosure may also be used to reduce dwell track locations because the ramp load and unload times are accurately known. The techniques described in this disclosure may also be used to perform axial run-out checks, and eliminate a test station during manufacture.
Further, the techniques described in this disclosure may also be used to determine a ramp contact radius. That is, optimizing the ramp load/unload detection may mitigate potential head/media contact, media damage, and particle generation.
In addition, the techniques described in this disclosure may also be used to detect individual heads or head gimbal assembly contact.
The techniques described in this disclosure may also be used to determine that the actuator is on the ramp during ramp unload and thus optimize acoustics.
The techniques described in this disclosure may be implemented in hardware, software, firmware, or any combination thereof. In particular, the techniques may be implemented in a hardware device that may include software and/or firmware to support the implementation. For portions implemented in software, the techniques may be realized in part by a computer-readable medium comprising program code containing instructions that, when executed, performs one or more of the methods described above. In this case, the computer readable medium may comprise random access memory (RAM) such as synchronous dynamic random access memory (SDRAM), read-only memory (ROM), non-volatile random access memory (NVRAM), electrically erasable programmable read-only memory (EEPROM), FLASH memory, magnetic or optical data storage media, and the like.
The program code may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, an application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. In this sense, the techniques are implemented in hardware, whether implemented entirely in hardware or in hardware such as a processor executing computer-readable code. The term “processor,” as used herein may refer to any of the foregoing structure or any other structure suitable for implementation of the techniques described herein.
The implementations described above and other implementations are within the scope of the following claims.
