CN105244046A - 划定数据磁道以避开热粗糙的磁盘驱动器 - Google Patents

划定数据磁道以避开热粗糙的磁盘驱动器 Download PDF

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CN105244046A
CN105244046A CN201510643171.0A CN201510643171A CN105244046A CN 105244046 A CN105244046 A CN 105244046A CN 201510643171 A CN201510643171 A CN 201510643171A CN 105244046 A CN105244046 A CN 105244046A
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G·S·V·塞瓦拉吉
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    • G11B5/58—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
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    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10—Digital recording or reproducing
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Abstract

一种划定数据磁道以避开热粗糙的磁盘驱动器。公开了一种磁盘驱动器，其包括在包括多个数据磁道的磁盘上方致动的磁头，其中磁头包括写入元件和读取元件。目标数据磁道中的粗糙被检测，并且接近目标数据磁道的数据磁道范围被划定，其中数据磁道范围在目标数据磁道的径向位置处跨越读取元件和写入元件之间的径向偏移的至少两倍。

Description

划定数据磁道以避开热粗糙的磁盘驱动器
本申请是于2012年6月25日提交的名称为“划定数据磁道以避开热粗糙的磁盘驱动器”的中国专利申请201210213710.3的分案申请。
背景技术
磁盘驱动器包括磁盘和连接到致动器臂的远端的磁头，所述致动器臂通过音圈电动机(VCM)绕枢轴旋转以将磁头径向定位在磁盘上方。磁盘包括多个径向间隔的同心磁道，用于记录用户数据扇区和嵌入的伺服扇形。嵌入的伺服扇区包括磁头定位信息(例如，磁道ID)，其由磁头读取并由伺服控制器处理以在致动器臂进行磁道到磁道的寻道时控制其速率。
图1示出磁盘2的现有技术格式，其包括由嵌入的伺服扇区60-6N限定的多个同心伺服磁道4。每个伺服扇区(例如，伺服扇区64)包括用于同步增益控制和定时恢复的前导码8、用于同步至具有粗略的磁头定位信息(例如，灰度编码磁道ID(Graycodedtrack))的数据字段12的同步标记10和提供精细磁头定位信息的伺服脉冲14。
当磁盘高速旋转时，磁头和磁盘之间形成空气轴承，从而磁头刚好紧密接近地悬浮在磁盘表面上方。由于磁盘的制造缺陷、污染，诸如粉尘颗粒、由于磁头沿加载/卸载斜面滑动产生的磨擦颗粒等等，磁盘表面上可能出现粗糙。如果磁头撞击粗糙，则其会升高磁头的温度(从而称为术语热粗糙)，产生不可靠的写入/读取性能和对磁头的物理损害。
附图说明
图1示出现有技术磁盘格式，其包括由嵌入的伺服扇区定义的多个伺服磁道。
图2A示出根据本发明的实施例的磁盘驱动器，其包括在磁盘上方致动的磁头。
图2B示出根据本发明实施例的磁头，其包括读取元件和写入元件，两者根据磁头的径向位置径向偏移。
图2C是根据本发明的实施例的流程图，其中，当在目标数据磁道中检测到粗糙时，划定接近目标数据磁道的数据磁道范围，其中该数据磁道范围在目标数据磁道的径向位置处跨越读取元件和写入元件之间的径向偏移的至少两倍。
图3A示出本发明的一个实施例，其中围绕粗糙划定的数据磁道的范围跨越读取元件和写入元件之间的径向偏移的两倍。
图3B示出本发明的一个实施例，其中所划定的数据磁道的范围增加到读取元件和写入元件之间的径向偏移的三倍以考虑磁头的极尖。
图4示出本发明的一个实施例，其中所划定的数据磁道的范围延伸到下一伺服磁道。
图5示出本发明的一个实施例，其中当读取元件和写入元件之间的径向偏移基本为零时，所划定的数据磁道的范围跨越磁头的宽度。
图6示出本发明的一个实施例，其中当读取元件和写入元件之间的径向偏移基本为零时，长寻道距离由划定的数据磁道范围限定。
图7示出根据本发明实施例的流程图，其中当命令寻道距离大于长寻道距离时，寻道期间磁头的悬浮高度增加以避开任何可能的粗糙。
具体实施方式
图2A示出根据本发明实施例的磁盘驱动器，其包括具有多个数据磁道18的磁盘16和在磁盘16上方致动的磁头20，其中磁头20包括写入元件22A和读取元件22B(图2B)。磁盘驱动器进一步包括控制电路24，其可操作以执行图2C的流程图，其中粗糙/微凸体(asperity)在目标数据磁道中被检测(步骤26)。接近目标数据磁道的数据磁道范围被划定(步骤28)，其中数据磁道范围(RANGE)在目标数据磁道的径向位置处跨越读取元件和写入元件之间的径向偏移(RW_OFFSET)的至少两倍。
在图2A的实施例中，磁盘16包括嵌入伺服扇区300-30N，其限定多个数据磁道18。控制电路24处理从磁头20发出的读取信号32以解调制伺服扇区300-30N并生成方位误差信号(PES)，该信号表示磁头的实际方位和相对于目标磁道的目标方位之间的误差。控制电路24使用适合的补偿滤波器滤波PES以生成施加给音圈电动机(VCM)36的控制信号34，音圈电动机36绕枢轴旋转致动器臂38以在减少PES的方向在磁盘的上方径向致动磁头20。伺服扇区300-30N可以包括任何适合的方位信息，例如用于粗略定位的磁道地址和用于精确定位的伺服脉冲。
在图2B的实施例中，沿数据磁道的长度在写入元件22A和读取元件22B之间存在间隙，其导致取决于磁头20的径向位置和磁头20的对应偏斜角的写入元件22A与读取元件22B之间的径向偏移。如图2B所示，在一个实施例中，径向偏移随着磁头离开磁盘的中间直径(MD)向外直径(OD)或者内直径(ID)移动而增加。在其他实施例中，当存在零度偏斜角(由于物理未对准)，使得朝向OD的径向偏移可能不同于朝向ID的径向偏移时，写入元件22A可能相对读取元件22B被径向偏移。取决于磁头的径向位置，径向偏移可跨度多个数据磁道。为了说明此径向偏移，伺服系统中引入啮合(jog)值，从而在写操作期间，在第一径向位置伺服读取元件22B以将写入元件22A定位在目标数据磁道上方。径向偏移在致动器臂的冲程(stroke)内被测量(估算)，从而可基于要写入的目标数据磁道获取相应的啮合值。在一个实施例中，控制电路在跨磁盘的多个分散的位置测量径向偏移，然后外推数据，从而估算对于任何给定的数据磁道的径向偏移。
图3A示出本发明的一个实施例，其中在数据磁道N检测到热粗糙。可以使用任何适合的技术检测热粗糙，例如通过估算读取信号中由于读取元件22B撞击热粗糙而产生的摄动。例如，当读取元件22B撞击粗糙时，由于热效应，读取信号的振幅中可能存在激增。这是为什么磁盘上的粗糙通常被称为热粗糙的原因。
在本发明的各实施例中，围绕粗糙划定(mapout)数据磁道的范围，从而避免与粗糙接触。所划定的数据磁道范围基于写入元件22A和读取元件22B之间的径向偏移。在图3A的实施例中，所划定的数据磁道的范围跨越写入元件22A和读取元件22B之间的径向偏移的至少两倍。以这种方式，写入元件22A和读取元件22B都应该不会接触数据磁道N中的粗糙(忽略偏离磁道伺服误差(off-trackservoerror))。在图3A的示例中，写入元件和读取元件之间的径向偏移(啮合)跨度四个数据磁道，因此在数据磁道N的两侧上划定四个数据磁道(即，划定数据磁道N-4到N+4)。当使用写入元件向数据磁道N-5写入时，在数据磁道N-1上方伺服读取元件，从而避免撞击数据磁道N中的粗糙。当使用读取元件读取数据磁道N+5时，写入元件将被定位在数据磁道N+1，从而避免撞击数据磁道N中的粗糙。在一个实施例中，可以围绕粗糙划定多个额外的数据磁道以考虑在磁盘上方粗糙附近伺服磁头时可能发生的偏离磁道误差。
如图3A中所示，基于啮合值的两倍围绕粗糙划定的数据磁道的范围可能无法防止磁头的极尖(拐角)撞击热粗糙。因此，在一个实施例中，该范围可以延伸到啮合值的三倍，如图3B所示，以考虑极尖(即，在图3B中划定数据磁道N-6到N+6)。当使用写入元件向数据磁道N–7写入时，在数据磁道N-3上方伺服读取元件，从而避免极尖撞击数据磁道N中的粗糙。当使用读取元件读取数据磁道N+7时，写入元件将被定位在数据磁道N+3，并由此避免极尖撞击数据磁道N中的粗糙。在一个实施例中，可以围绕粗糙划定多个额外的数据磁道以考虑在磁盘上方粗糙附近伺服磁头时可能发生的偏离磁道误差。
在一个实施例中，伺服磁道的密度小于数据磁道，从而可以在连续的伺服磁道之间限定多个数据磁道。图4示出这种实施例的示例，其中对于至少部分磁盘表面，在每个伺服磁道之间记录四个数据磁道。在一个实施例中，围绕粗糙划定的数据磁道的范围包括第一范围和第二范围，第一范围是读取元件和写入元件之间的径向偏移的至少两倍，第二范围包括由第一范围的边界和下一个伺服磁道限定的多个数据磁道。在图4中所示的示例性实施例中，第一范围包括读取元件和写入元件之间的径向偏移的至少三倍(三倍的啮合值)，并且第二范围包括由第一范围的边界和下一个伺服磁道所限定的数据磁道(即，延伸达到伺服磁道N-2和伺服磁道N+3)。此实施例通过使用边界伺服磁道不伺服磁头的方式提供额外余量(margin)，由此有助于避免由于偏离磁道伺服误差而撞击热粗糙。
图5示出本发明的示例实施例，其中当读取元件和写入元件之间的径向偏移接近最小时(例如，磁头靠近磁盘的中间直径时)，围绕数据磁道N中的粗糙所划定的数据磁道的范围至少跨越磁头的宽度，从而避免磁头在存取数据磁道N-4和N+4时撞击热粗糙。在一个实施例中，可以延伸数据磁道的范围以考虑如上所述的偏离磁道伺服误差，同时考虑估算磁头宽度中的误差或者当径向偏移基本为零时由于读取元件相对于写入元件物理未对准而产生的磁头偏斜的可能性。
磁头可包括适当的悬浮高度致动器，例如适当的加热器或者微致动器(例如，压电微致动器)，并且在一个实施例中，当磁头跨磁盘表面寻道时，控制电路增加磁头的悬浮高度，从而避免磁头撞击粗糙。在进行具有的寻道距离大于鉴于粗糙所划定的最小磁道范围(称为长寻道距离)的任何寻道操作之前，控制电路增加悬浮高度。在一个实施例中，长寻道距离对应于当读取元件和写入元件之间的径向偏移接近最小的时候。图6显示一实施例，其中当接近磁盘的中间直径定位磁头时，径向偏移接近最小，其也对应于围绕粗糙所划定的最小数目的数据磁道。所划定的数据磁道的数目由于如上所述的磁头的偏斜角而向磁盘的外直径和内直径增加，但是如图6中所示，长寻道距离跨磁盘表面保持不变。
参考图7的流程图理解此实施例，其中产生相应于当读取元件和写入元件之间的径向偏移接近最小时的长寻道距离(LSD)(步骤40)。在将要执行存取命令(步骤42)时，针对存取命令确定命令寻道距离(CSD)(步骤44)。当CSD小于LSD(步骤46)时，控制电路使磁头寻道命令寻道距离(步骤48)，而不增加磁头的悬浮高度。当CSD大于LSD(步骤46)时，控制电路增加磁头的悬浮高度(步骤50)，使磁头寻道命令寻道距离(步骤52)，之后降低磁头的悬浮高度(步骤54)。
增加悬浮高度帮助防止磁头撞击粗糙，因为任何大于LSD的寻道都有可能跨越粗糙。与保持粗糙位置的绘图且之后基于粗糙绘图调整悬浮高度相比，此实施例实现起来相对简单。当命令寻道距离小于LSD时，不需要增加悬浮高度，因为磁头试图在没有由于先前检测的粗糙而划定的范围内存取数据磁道，并且由此磁头在寻道期间不会跨越先前检测的粗糙。
可以采用任何适合的控制电路来实现本发明的实施例中的流程图，例如采用任何适合的集成电路或多个集成电路。例如，可以在读取通道集成电路内或者在与读取通道分离的部件如磁盘控制器中实现控制电路，或者如上所述的某些步骤可以由读取通道执行，而其他步骤由磁盘控制器执行。在一个实施例中，读取通道和磁盘控制器实现为单独的集成电路，并且在可替换的实施例中，其被制作到单个集成电路或者片上系统(SOC)中。此外，控制电路可以包括适合的前置放大器电路，其实现为单独的集成电路、集成到读取通道或者磁盘控制器电路中或者集成到SOC中。
在一个实施例中，控制电路包括执行指令的微处理器，这些指令可操作以使微处理器执行本文所述的流程图的各步骤。这些指令可以存储在任何计算机可读介质中。在一个实施例中，他们可以存储在微处理器外的或者与SOC中的微处理器集成的非易失性半导体存储器上。在另一个实施例中，这些指令存储在磁盘上，并且当磁盘驱动器通电时被读取到易失性半导体存储器中。在又一实施例中，控制电路包括适当的逻辑电路，比如状态机电路。

Claims (10)

1.一种磁盘驱动器，包括：
磁盘，其包括多个数据磁道；
磁头，其在所述磁盘上方致动，其中所述磁头包括写入元件和读取元件；和
控制电路，其可操作以：
生成长寻道距离，其相应于当所述读取元件和所述写入元件之间的径向偏移接近最小的时候；
响应命令寻道距离使所述磁头在所述磁盘上方径向寻道；和
当所述命令寻道距离大于所述长寻道距离时，在寻道期间增加所述磁头的悬浮高度。
2.根据权利要求1所述的磁盘驱动器，其中所述控制电路进一步地可操作以：
检测目标数据磁道中的粗糙；和
划定接近所述目标数据磁道的数据磁道范围，其中所述数据磁道范围在所述目标数据磁道的径向位置处跨越所述读取元件和所述写入元件之间的径向偏移的至少两倍。
3.根据权利要求2所述的磁盘驱动器，其中所述数据磁道范围跨越所述读取元件和所述写入元件之间的所述径向偏移的至少三倍。
4.根据权利要求2所述的磁盘驱动器，其中：
所述磁盘包括由伺服扇区限定的多个伺服磁道；
所述伺服磁道的密度小于所述数据磁道；并且
所述数据磁道范围跨越：
第一范围，其至少是所述读取元件和所述写入元件之间的所述径向偏移的两倍；和
第二范围，其包括由所述第一范围的边界和下一伺服磁道限定的多个数据磁道。
5.根据权利要求2所述的磁盘驱动器，其中所述控制电路进一步可操作以在遍及所述磁盘的多个径向位置处测量所述读取元件和所述写入元件之间的所述径向偏移。
6.一种操作磁盘驱动器的方法，所述磁盘驱动器包括磁头，其在包括多个数据磁道的磁盘上方致动，其中所述磁头包括写入元件和读取元件，所述方法包括：
生成长寻道距离，其相应于当所述读取元件和所述写入元件之间的径向偏移接近最小的时候；
响应命令寻道距离，使所述磁头在所述磁盘上方径向寻道；和
当所述命令寻道距离大于所述长寻道距离时，在寻道期间增加所述磁头的悬浮高度。
7.根据权利要求6所述的方法，进一步包括：
检测目标数据磁道中的粗糙；和
划定接近所述目标数据磁道的数据磁道范围，其中所述数据磁道范围在所述目标数据磁道的径向位置处跨越所述读取元件和所述写入元件之间所述径向偏移的至少两倍。
8.根据权利要求7所述的方法，其中所述数据磁道范围跨越所述读取元件和所述写入元件之间的所述径向偏移的至少三倍。
9.根据权利要求7所述的方法，其中：
所述磁盘包括由伺服扇区限定的多个伺服磁道；
所述伺服磁道的密度小于所述数据磁道；和
所述数据磁道范围跨越：
第一范围，其至少是所述读取元件和所述写入元件之间的所述径向偏移的两倍；和
第二范围，其包括由所述第一范围的边界和下一伺服磁道限定的多个数据磁道。
10.根据权利要求7所述的方法，进一步包括在遍及所述磁盘的多个径向位置处测量所述读取元件和所述写入元件之间的径向偏移。
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