公开(公告)号：US4879708A

公开(公告)日：1989-11-07

申请号：US147906

申请日：1988-01-25

申请人： Kurt W. Getreuer ,  Johannes J. Verboom

发明人： Kurt W. Getreuer ,  Johannes J. Verboom

IPC分类号： G11B7/007 ,  G11B7/085 ,  G11B7/09

CPC分类号： G11B7/0938 ,  G11B7/00745 ,  G11B7/08517 ,  G11B7/08541

摘要： An optical disk recording system including a record medium is disclosed for providing an accurate track crossing count and an accurate track following signal. A first embodiment utilizes off-centered wobbled areas located in the headers of the record medium. The high frequency content of a first signal is combined with the low frequency content of a second signal, which is generated using the wobbled areas. In another embodiment, light-reflective discontinuities are provided in the header areas of the record medium. A qualifier and an AGC are utilized in providing a corrected track following signal. In still another embodiment, reflective discontinuities are located in the servo areas of the record medium. In such an embodiment, it is preferred that there is a fixed gain adjustment to a radial push-pull signal. With regard to each of the three aforesaid embodiments, a track following signal is corrected to compensate for aberrations that are caused by a shift of the light beam returned from the record medium surface. In yet another embodiment, the track following signal is generated using only the central aperture or wobble signal. In this embodiment, it is preferred that three pits be utilized in connection with the track following operation. The three pits are provided in two servo bytes of information located in the servo areas. Two of the three bits are wobble pits and the third pit is used in clocking.

摘要翻译： 公开了一种包括记录介质的光盘记录系统，用于提供准确的轨道交叉计数和准确跟踪信号。 第一实施例使用位于记录介质的头部中的偏心摆动区域。 第一信号的高频内容与使用摆动区域产生的第二信号的低频内容组合。 在另一个实施例中，在记录介质的标题区域中提供光反射不连续性。 使用限定符和AGC来提供校正后的跟踪信号。 在另一个实施例中，反射不连续性位于记录介质的伺服区域中。 在这样的实施例中，优选的是对径向推挽信号进行固定增益调整。 对于上述三个实施例中的每一个，对跟踪跟踪信号进行校正，以补偿由从记录介质表面返回的光束的偏移引起的像差。 在另一个实施例中，仅使用中心孔径或摆动信号产生跟踪信号。 在该实施例中，优选地，跟踪跟踪操作结合使用三个凹坑。 三个凹坑位于伺服区域的两个伺服字节的信息中。 三位中的两位是摆动凹坑，第三个凹坑用于计时。

公开(公告)号：US4879707A

公开(公告)日：1989-11-07

申请号：US148028

申请日：1988-01-25

申请人： Kurt W. Getreuer ,  Johannes J. Verboom ,  Pierre R. Sonneville

发明人： Kurt W. Getreuer ,  Johannes J. Verboom ,  Pierre R. Sonneville

IPC分类号： G11B7/007 ,  G11B7/085 ,  G11B7/09

CPC分类号： G11B7/0938 ,  G11B7/00745 ,  G11B7/08517 ,  G11B7/08541

摘要： An optical disk recording system including a record medium is disclosed for providing an accurate track crossing count and an accurate track following signal. A first embodiment utilizes off-centered wobbled areas located in the headers of the record medium. The high frequency content of a first signal is combined with the low frequency content of a second signal, which is generated using the wobbled areas. In another embodiment, light-reflective discontinuities are provided in the header areas of the record medium. A qualifier and an AGC are utilized in providing a corrected track following signal. In still another embodiment, reflective discontinuities are located in the servo areas of the record medium. In such an embodiment, it is preferred that there be a fixed gain adjustment to a radial push-pull signal. With regard to each of the three aforesaid embodiments, a track following signal is corrected to compensate for aberrations that are caused by a shift of the light beam returned from the record medium surface. In yet another embodiment, the track following signal is generated using only the central aperture or wobble signal. In this embodiment, it is preferred that three pits be utilized in connection with the track following operation. The three pits are provided in two servo bytes of information located in the servo areas. Two of the three pits are wobble pits and the third pit is used in clocking.

摘要翻译： 公开了一种包括记录介质的光盘记录系统，用于提供准确的轨道交叉计数和准确跟踪信号。 第一实施例使用位于记录介质的头部中的偏心摆动区域。 第一信号的高频内容与使用摆动区域产生的第二信号的低频内容组合。 在另一个实施例中，在记录介质的标题区域中提供光反射不连续性。 使用限定符和AGC来提供校正后的跟踪信号。 在另一个实施例中，反射不连续性位于记录介质的伺服区域中。 在这样的实施例中，优选的是对径向推挽信号进行固定增益调整。 对于上述三个实施例中的每一个，对跟踪跟踪信号进行校正，以补偿由从记录介质表面返回的光束的偏移引起的像差。 在另一个实施例中，仅使用中心孔径或摆动信号产生跟踪信号。 在该实施例中，优选地，跟踪跟踪操作结合使用三个凹坑。 三个凹坑位于伺服区域的两个伺服字节的信息中。 三个凹坑中的两个是摆动凹坑，第三个凹坑用于计时。

公开(公告)号：US4779253A

公开(公告)日：1988-10-18

申请号：US902278

申请日：1986-08-29

申请人： Kurt W. Getreuer ,  Johannes J. Verboom ,  David L. Schell ,  David E. Lewis

发明人： Kurt W. Getreuer ,  Johannes J. Verboom ,  David L. Schell ,  David E. Lewis

IPC分类号： G11B7/00 ,  G11B7/004 ,  G11B7/005 ,  G11B7/0065 ,  G11B7/007 ,  G11B7/013 ,  G11B7/085 ,  G11B7/09 ,  G11B7/24 ,  G11B21/10

CPC分类号： G11B7/085 ,  G11B7/0901 ,  G11B7/0938 ,  G11B7/24085

摘要： Sampled servo data comprising one pit centered on a track and two pits spaced 1/4 track pitch from track center on opposite sides thereof provide for two sinusoidal tracking signals, one radially phase offset from the other by 90 degrees. A first tracking signal derived from subtracting the signals of the offset pits has a zero crossing at track center and is used by the servo system for tracking. Its derivative is used for damping. A second tracking signal derived from all three pits has maxima at track centers and is therefore 90 degrees out of phase with the first tracking signal. This second signal provides track crossing information, and when used in quadrature with the first tracking signal, provides information about the radial direction of crossing. The second signal also provides a control signal for inverting the damping signal while between tracks when the derivative of the first tracking signal would ordinarily be negative and provide for negative damping.

摘要翻译： 包括以轨道为中心的一个凹坑的采样伺服数据和在其相对侧上从轨道中心间隔开1/4轨道间距的两个凹坑提供两个正弦跟踪信号，一个径向相位偏移90度。 从减去偏移坑的信号得到的第一跟踪信号在轨道中心处具有过零点，并被伺服系统用于跟踪。 其导数用于阻尼。 从所有三个凹坑导出的第二跟踪信号在轨道中心处具有最大值，因此与第一跟踪信号相差90度。 该第二信号提供轨道交叉信息，并且当与第一跟踪信号正交使用时，提供关于横向的径向方向的信息。 当第一跟踪信号的导数通常为负并且提供负阻尼时，第二信号还提供用于在磁道之间反转阻尼信号的控制信号。

公开(公告)号：US07586831B2

公开(公告)日：2009-09-08

申请号：US11085721

申请日：2005-03-21

申请人： Johannes J. Verboom ,  Kurt W. Getreuer

发明人： Johannes J. Verboom ,  Kurt W. Getreuer

IPC分类号： G11B7/24

CPC分类号： G11B7/0053 ,  G11B7/00745 ,  G11B7/24038 ,  G11B7/24082

摘要： In order to help maximize the capacity of an optical storage device, and increase the efficiency of addressing, a unique addressing scheme is utilized to provide addressing for an optical storage disk. Importantly, this scheme is compatible with multilayer disks and helps to minimize the potential for errors. In the addressing scheme of the present invention, the storage media is provided with a wobbled groove, which includes addressing information for the media. More specifically, the surface of the media is divided into predetermined sections, or portions, each portion having a selected number of wobble periods. Within these wobble periods, the amplitude of one single wobble period is either reduced or eliminated. The location of this reduced or eliminated wobble signal can then be determined by the readout system of the present invention and utilized to provide addressing information. A look-up table is provided, which includes a corresponding address value for each predetermined wobble period within a defined address frame. By determining the location of the zero or reduced wobble period within the address frame, an address value can be determined by that particular frame period by providing a number of frames adjacent to one another, a specific address is provided. Utilizing this mechanism, robust detection is provided since a differential detection can be easily utilized, and complex modulation techniques are not required.

摘要翻译： 为了帮助最大限度地提高光存储设备的容量，并提高寻址的效率，采用独特的寻址方案为光存储盘提供寻址。 重要的是，该方案与多层磁盘兼容，有助于最大程度地减少错误的可能性。 在本发明的寻址方案中，存储介质设置有摆动凹槽，其包括介质的寻址信息。 更具体地，介质的表面被划分成预定部分或部分，每个部分具有选定数量的摆动周期。 在这些摆动周期内，一个摆动周期的振幅被减小或消除。 然后可以通过本发明的读出系统确定该减少或消除的摆动信号的位置，并用于提供寻址信息。 提供了一个查找表，其包括在定义的地址帧内的每个预定摆动周期的相应地址值。 通过确定地址帧内的零或减少的摆动周期的位置，可以通过提供彼此相邻的多个帧来确定地址值，该地址值由该特定帧周期确定，提供特定的地址。 利用这种机制，由于可以容易地利用差分检测，因此不需要复杂的调制技术，所以提供鲁棒的检测。

公开(公告)号：US5031166A

公开(公告)日：1991-07-09

申请号：US410607

申请日：1989-09-21

申请人： Kurt W. Getreuer ,  Johannes J. Verboom ,  Sonneville, Pierre R.

发明人： Kurt W. Getreuer ,  Johannes J. Verboom ,  Sonneville, Pierre R.

IPC分类号： G11B7/007 ,  G11B7/085 ,  G11B7/09

CPC分类号： G11B7/08541 ,  G11B7/00745 ,  G11B7/08517 ,  G11B7/0938

摘要： An optical disk recording system including a record medium is disclosed for providing an accurate track crossing count and an accurate track following signal. A first embodiment utilizes off-centered wobbled areas located in the headers of the record medium. The high frequency content of a first signal is combined with the low frequency content of a second signal, which is generated using the wobbled areas. In another embodiment, light-reflective discontinuities are provided in the header areas of the record medium. A qualifier and an AGC are utilized in providing a corrected track following signal. In still another embodiment, reflective discontinuities are located in the servo areas of the record medium. In such an embodiment, it is preferred that there be a fixed gain adjustment to a radial push-pull signal. With regard to each of the three aforesaid embodiments, a track following signal is corrected to compensate for aberrations that are caused by a shift of the light beam returned from the record medium surface. In yet another embodiment, the track following signal is generated using only the central aperture or wobble signal. In this embodiment, it is preferred that three pits be utilized in connection with the track following operation. The three pits are provided in two servo bytes of information located in the servo areas. Two of the three pits are wobble pits and the third pit is used in clocking.

摘要翻译： 公开了一种包括记录介质的光盘记录系统，用于提供准确的轨道交叉计数和准确跟踪信号。 第一实施例使用位于记录介质的头部中的偏心摆动区域。 第一信号的高频内容与使用摆动区域产生的第二信号的低频内容组合。 在另一个实施例中，在记录介质的标题区域中提供光反射不连续性。 使用限定符和AGC来提供校正后的跟踪信号。 在另一个实施例中，反射不连续性位于记录介质的伺服区域中。 在这样的实施例中，优选的是对径向推挽信号进行固定增益调整。 对于上述三个实施例中的每一个，对跟踪跟踪信号进行校正，以补偿由从记录介质表面返回的光束的偏移引起的像差。 在另一个实施例中，仅使用中心孔径或摆动信号产生跟踪信号。 在该实施例中，优选地，跟踪跟踪操作结合使用三个凹坑。 三个凹坑位于伺服区域的两个伺服字节的信息中。 三个凹坑中的两个是摆动凹坑，第三个凹坑用于计时。

公开(公告)号：US4914645A

公开(公告)日：1990-04-03

申请号：US147690

申请日：1988-01-25

申请人： Kurt W. Getreuer ,  Johannes J. Verboom ,  David L. Schell ,  David E. Lewis ,  Gregory V. Hofer ,  Kathleen M. Connelly ,  James C. McDonald ,  Pierre R. Sonneville ,  Cees van Nimwegen

发明人： Kurt W. Getreuer ,  Johannes J. Verboom ,  David L. Schell ,  David E. Lewis ,  Gregory V. Hofer ,  Kathleen M. Connelly ,  James C. McDonald ,  Pierre R. Sonneville ,  Cees van Nimwegen

IPC分类号： G11B7/24 ,  G11B7/00 ,  G11B7/004 ,  G11B7/0065 ,  G11B7/007 ,  G11B7/013 ,  G11B7/085 ,  G11B7/09

CPC分类号： G11B7/0938 ,  G11B7/085 ,  G11B7/0901 ,  G11B7/24085

摘要： An optical disk recording system including a record medium is disclosed for providing an accurate track crossing count and an accurate track following signal. A first embodiment utilizes off-centered wobbled areas located in the headers of the record medium. The high frequency content of a first signal is combined with the low frequency content of a second signal, which is generated using the wobbled areas. In another embodiment, light-reflective discontinuities are provided in the header areas of the record medium. A qualifier and an AGC are utilized in providing a corrected track following signal. In still another embodiment, reflective discontinuities are located in the servo areas of the record medium. In such an embodiment, it is preferred that there is a fixed gain adjustment to a radial push-pull signal. With regard to each of the three aforesaid embodiments, a track following signal is corrected to compensate for aberrations that are caused by a shift of the light beam returned from the record medium surface. In yet another embodiment, the track following signal is generated using only the central aperture or wobble signal. In this embodiment, it is preferred that three pits be utilized in connection with the track following operation. The three pits are provided in two servo bytes of information located in the servo areas. Two of the three pits are wobble pits and the third pit is used in clocking.

摘要翻译： 公开了一种包括记录介质的光盘记录系统，用于提供准确的轨道交叉计数和准确跟踪信号。 第一实施例使用位于记录介质的头部中的偏心摆动区域。 第一信号的高频内容与使用摆动区域产生的第二信号的低频内容组合。 在另一个实施例中，在记录介质的标题区域中提供光反射不连续性。 使用限定符和AGC来提供校正后的跟踪信号。 在另一个实施例中，反射不连续性位于记录介质的伺服区域中。 在这样的实施例中，优选的是对径向推挽信号进行固定增益调整。 对于上述三个实施例中的每一个，对跟踪跟踪信号进行校正，以补偿由从记录介质表面返回的光束的偏移引起的像差。 在另一个实施例中，仅使用中心孔径或摆动信号产生跟踪信号。 在该实施例中，优选地，跟踪跟踪操作结合使用三个凹坑。 三个凹坑位于伺服区域的两个伺服字节的信息中。 三个凹坑中的两个是摆动凹坑，第三个凹坑用于计时。

公开(公告)号：US6122232A

公开(公告)日：2000-09-19

申请号：US8989

申请日：1998-01-20

申请人： David L. Schell ,  Randolph S. Crupper ,  Marvin B. Davis ,  Kurt W. Getreuer ,  Leonardus J. Grassens ,  David E. Lewis

发明人： David L. Schell ,  Randolph S. Crupper ,  Marvin B. Davis ,  Kurt W. Getreuer ,  Leonardus J. Grassens ,  David E. Lewis

IPC分类号： G11B7/0045 ,  G02B7/04 ,  G11B5/55 ,  G11B7/00 ,  G11B7/0037 ,  G11B7/004 ,  G11B7/005 ,  G11B7/007 ,  G11B7/085 ,  G11B7/09 ,  G11B7/125 ,  G11B7/135 ,  G11B11/105 ,  G11B15/467 ,  G11B17/04 ,  G11B19/28 ,  G11B20/10 ,  G11B20/12 ,  G11B21/02 ,  G11B21/10 ,  G11B25/04 ,  G11B33/08 ,  H02K41/035 ,  H03B5/08 ,  H03B5/12

CPC分类号： G11B17/043 ,  G11B11/10504 ,  G11B11/10534 ,  G11B11/1055 ,  G11B11/10563 ,  G11B11/10576 ,  G11B11/10595 ,  G11B17/0438 ,  G11B20/10009 ,  G11B21/10 ,  G11B21/106 ,  G11B5/5526 ,  G11B7/0037 ,  G11B7/004 ,  G11B7/08511 ,  G11B7/08529 ,  G11B7/08582 ,  G11B7/09 ,  G11B7/0908 ,  G11B7/0917 ,  G11B7/093 ,  G11B7/0932 ,  G11B7/0933 ,  G11B7/0935 ,  G11B7/0941 ,  G11B7/0943 ,  G11B7/0945 ,  G11B7/126 ,  G11B7/1356 ,  H02K41/0354 ,  G11B20/10037 ,  G11B20/10222 ,  G11B20/1258 ,  G11B20/14 ,  G11B2007/0919 ,  G11B2020/10916 ,  G11B2020/1281 ,  G11B2020/1484 ,  G11B7/00456 ,  G11B7/00745 ,  G11B7/0901 ,  H02K41/0356

摘要： A mechanical isolation apparatus suited for mitigating the effects of undesired mechanical forces upon disc drive system components, such as those found in compact disc, laser disc, magneto-optical player/recorder devices and similar devices. Component members are provided for mitigating the effects of compressive forces, vibration isolation, and thermal expansion, and may include compression ribs mounted on a housing for absorbing compressive forces. The housing is preferably adapted to fit on the end of a pole piece assembly. A crash stop may also be provided as a shock absorbing bumper and isolator to prevent a moving carriage from crashing into a solid surface. The compressive ribs and the crash stop are made of a material that exhibits minimum creep, such as a silicon rubber, polyurethane, or injection molded plastic.

摘要翻译： 一种机械隔离装置，适用于减轻不期望的机械力对磁盘驱动器系统部件的影响，例如在光盘，激光盘，磁光播放器/记录器装置和类似装置中发现的那些。 提供了用于减轻压缩力，隔振和热膨胀的影响的组件构件，并且可以包括安装在壳体上用于吸收压缩力的压缩肋。 壳体优选适于装配在极片组件的端部上。 还可以提供碰撞停止件作为减震保险杠和隔离器，以防止移动的滑架撞击到固体表面。 压缩肋和紧急停止件由表现出最小蠕变的材料制成，例如硅橡胶，聚氨酯或注模塑料。

公开(公告)号：US5986983A

公开(公告)日：1999-11-16

申请号：US971875

申请日：1997-11-19

申请人： Charles J. Simpson ,  Philip F. Marino ,  Kurt W. Getreuer

发明人： Charles J. Simpson ,  Philip F. Marino ,  Kurt W. Getreuer

IPC分类号： G11B7/09 ,  G11B7/095 ,  G11B7/00

CPC分类号： G11B7/0956 ,  G11B7/0933 ,  G11B7/0935 ,  G11B7/093

摘要： An optical actuator adapted to control the position of the actuator in at least two degrees of freedom of motion. The actuator includes a base, a moveable lens holder having a lens, a structure for connecting the lens holder to the base to support movement of the lens holder, and first and second pairs of surface-field motors, each pair of surface-field motors having first and second surface-field motors, each first and second surface-field motor including a surface-field coil and a surface-field magnetic assembly for applying forces to the lens holder to move the lens holder in at least two degrees of freedom of motion relative to the base, the surface-field coil being mounted on either the base or the lens holder, and the corresponding surface-field magnetic assembly being oppositely mounted on either the lens holder or the base to interact with the surface-field coil. Each surface-field magnetic assembly includes two pairs of opposing poles with one pair of opposing poles facing the corresponding surface-field coil, the opposing poles of each pair being separated by a pole dividing line so that the pole dividing lines of the opposing poles facing the surface-field coils of the surface-field magnetic assemblies of the first surface-field motor extend and intersect at a point above the surface-field coils, and the pole dividing lines of the opposing poles facing the surface-field coils of the surface-field magnetic assemblies of the second surface-field motor extend and intersect at a point below the surface-field coils. Currents are selectively applied to the surface-field coils so that the surface-field motors apply forces to the lens holder to control at least two degrees of freedom of motion of the lens holder relative to the base.

摘要翻译： 适于在至少两个运动自由度中控制致动器的位置的光致动器。 致动器包括基座，具有透镜的可移动透镜保持器，用于将透镜保持器连接到基座以支撑透镜保持器的运动的结构，以及第一和第二对表面场马达，每对表面场马达 具有第一和第二表面场电动机，每个第一和第二表面场电动机包括表面场线圈和表面场磁性组件，用于向透镜保持器施加力以使透镜架以至少两个自由度移动 相对于基座的运动，表面场线圈安装在基座或透镜架上，并且相应的表面场磁性组件相对地安装在透镜架或底座上以与表面场线圈相互作用。 每个表面场磁性组件包括两对相对的极，其中一对相对的极面对着相应的表面场线圈，每对的相对的极通过极分割线分开，使得相对极的极分割线面对 第一表面场电动机的表面场磁性组件的表面场线圈在表面场线圈上方的一点上延伸并相交，并且相对极的极分界线面对表面的表面场线圈 第二表面场电动机的场磁组件在表面场线圈下方的点处延伸并相交。 选择性地将电流施加到表面场线圈，使得表面场电机将力施加到透镜架以控制透镜保持器相对于基座的至少两个自由度。

公开(公告)号：US5532989A

公开(公告)日：1996-07-02

申请号：US399268

申请日：1995-03-06

申请人： Kurt W. Getreuer ,  Leonardus J. Grassens

发明人： Kurt W. Getreuer ,  Leonardus J. Grassens

IPC分类号： G11B5/55 ,  G11B7/0037 ,  G11B7/004 ,  G11B7/007 ,  G11B7/085 ,  G11B7/09 ,  G11B7/135 ,  G11B11/105 ,  G11B17/04 ,  G11B20/10 ,  G11B20/12 ,  G11B21/10 ,  H02K41/035 ,  G11B7/00

CPC分类号： G11B5/5526 ,  G11B11/10563 ,  G11B17/043 ,  G11B17/0438 ,  G11B20/10009 ,  G11B21/10 ,  G11B21/106 ,  G11B7/0037 ,  G11B7/004 ,  G11B7/08529 ,  G11B7/08582 ,  G11B7/09 ,  G11B7/0908 ,  G11B7/0917 ,  G11B7/093 ,  G11B7/0932 ,  G11B7/0933 ,  G11B7/0935 ,  G11B7/0943 ,  G11B7/0945 ,  G11B7/1356 ,  H02K41/0354 ,  G11B11/10576 ,  G11B11/10595 ,  G11B20/1258 ,  G11B2007/0919 ,  G11B2020/10916 ,  G11B7/00745 ,  G11B7/0901 ,  H02K41/0356

摘要： An apparatus for optically reading or recording information on an optical disc which is rotatable about an axis of rotation. The apparatus includes a frame, a carriage, a carriage drive, an objective lens, an objective lens holder, a focus drive and a fine tracking drive. The objective lens is mounted on the objective lens holder so that the optical axis of the objective lens substantially intersects the center of mass of the carriage. The fine motor, used for tracking and focus, has a center of mass that substantially lies on the optical axis and proximate the center of mass of the carriage.

摘要翻译： 一种用于在可围绕旋转轴线旋转的光盘上光学读取或记录信息的装置。 该装置包括框架，托架，托架驱动器，物镜，物镜保持器，聚焦驱动器和精细跟踪驱动器。 物镜安装在物镜支架上，使得物镜的光轴基本上与托架的质心相交。 用于跟踪和聚焦的精细电机具有基本上位于光轴上并且靠近托架质心的质心。

公开(公告)号：US4855977A

公开(公告)日：1989-08-08

申请号：US78264

申请日：1987-07-27

申请人： Kurt W. Getreuer ,  David L. Schell

发明人： Kurt W. Getreuer ,  David L. Schell

IPC分类号： G11B7/085 ,  G11B21/08

CPC分类号： G11B7/08529 ,  G11B21/083

摘要： A track seeking method is provided which relies on sampled seek information. No external sensors are employed and the seek information is intermittently stored along the tracks provided on the disk surface. In determining the actual velocity of the seek actuator, at least two methods for counting crossed tracks are utilized. Preferably, a 1/2-count method is used at lower seek velocities and a 16-count method is used at higher seek velocities. The 178 -count method involves the receipt of two counts for each track that is crossed, while the 16-count method involves counting every sixteen tracks that are crossed. The selection of the 1/2-count and the 16-count methods for counting tracks crossed results in a velocity gap region. The velocity gap region is a range of seek actuator velocities in which the servo loop is underdamped for the 16-count method and where folding occurs for the 1/2-count method. To overcome the underdamping and folding problems, various solutions have been devised. In one embodiment, the velocity profile is configured so that the gap region is crossed in a relatively short amount of time and the 16-count method is used in providing velocity feedback.