Lateral tape motion detector
10 claims: 2 independent, 8 dependent
- 1記憶テープ駆動装置における記憶テープの横方向移動を検出するためのテープ縁部センサシステムであって、前記記憶テープは、第1のテープ縁部、第2のテープ縁部、第1のテープ側および第2のテープ側を有し、横方向テープ移動は、読取/書込動作中の記憶テープ移動の垂直方向における前記記憶テープの移動であり、前記テープ縁部センサシステムは、 第1の光信号を発する第1のフォトエミッタを含み、前記第1のフォトエミッタは、前記第1の光信号が変調もされるように、変調され、前記テープ縁部センサシステム は、 前記第1の光信号の一部を受取るよう位置決めされ、受取った前記第1の光信号の前記一部に比例する第1の検出された信号を与える第1の光検出器と、 第1の開口を規定する第1のバッフルとを さらに 含み、前記第1のバッフルは前記第1のフォトエミッタと前記第1の光検出器との間に配置され、前記第1の開口は、前記第1のテープ縁部に、横方向テープ移動が検出される第1の領域を規定し、前記第1のテープ縁部は前記第1の光信号を部分的に遮断し、それによって、前記第1の開口とともに、前記第1の光検出器によって受取られる前記第1の光信号の前記一部における変動が横方向テープ移動によって少なくとも一部生じるように、前記第1の光検出器によって受取られる前記第1の光信号の前記一部を規定し 、前記テープ縁部センサシステムはさらに、 第3の光信号を発する第3のフォトエミッタを含み、前記第3のフォトエミッタは、前記第3の光信号が変調もされるように、変調され、前記テープ縁部センサシステムは、 前記第3の光信号の一部を受取るよう位置決めされ、受取った前記第3の光信号の前記一部に比例する第3の検出された信号を与える第3の光検出器と、 第3の開口を規定する第3のバッフルとをさらに含み、前記第3のバッフルは前記第3のフォトエミッタと前記第3の光検出器との間に配置され、前記第3の開口は、前記第1のテープ縁部に、横方向テープ移動が検出される第3の領域を規定し、前記第1のテープ縁部は前記第3の光信号を部分的に遮断し、それによって、前記第3の開口とともに、前記第3の光検出器によって受取られる前記第3の光信号の前記一部における変動が横方向テープ移動によって少なくとも一部生じるように、前記第3の光検出器によって受取られる前記第3の光信号の前記一部を規定し、 前記テープ縁部センサシステムはさらに、 前記第1 および第3 のフォトエミッタ と、 前記第1 および第3 の光検出器 と に接続される帰還システムを含み、前記帰還システムは、前記第1 ならびに第3 のフォトエミッタの変調および前記第1 ならびに第3 の検出された信号のローパスフィルタ処理を与えて、ノイズおよび信号ドリフトからの干渉を最小限に し、前記テープ縁部センサシステムは、 前記記憶テープの横方向移動を安定させる安定部をさらに含み、 前記第1の光検出器は前記安定部に対して前方位置に位置し、前記第3の光検出器は前記安定部に対して後方位置に位置する、 テープ縁部センサシステム。
- 2第2の光信号を発する第2のフォトエミッタをさらに含み、前記第2のフォトエミッタは、前記第2の光信号が変調もされるように、変調され、前記テープ縁部センサシステムはさらに、 前記第2のフォトエミッタから前記第2の光信号の一部を受取るよう位置決めされ、受取った前記第2の光信号の前記一部に比例する第2の検出された信号を与える第2の光検出器と、 第2の開口を規定する第2のバッフルとを含み、前記第2のバッフルは前記第2のフォトエミッタと前記第2の光検出器との間に配置され、前記第2の開口は、前記第2のテープ縁部に、横方向テープ移動が検出される第2の領域を規定し、前記第2のテープ縁部は前記第2の光信号を部分的に遮断し、それによって、前記第2の開口とともに、前記第2の光検出器によって受取られる前記第2の光信号の前記一部における変動が横方向テープ移動によって少なくとも一部生じるように、前記第2の光検出器によって受取られる前記第2の光信号の前記一部を規定し、前記帰還システムは前記第2のフォトエミッタおよび前記第2の光検出器に接続し、前記帰還システムは、前記第2の光検出器の変調および前記第2の検出された信号のローパスフィルタ処理を与えて、ノイズおよび信号ドリフトからの干渉を最小限にする、請求項1に記載のテープ縁部センサシステム。
- 3第 4の光信号を発する第4のフォトエミッタをさらに含み、前記第4のフォトエミッタは、前記第4の光信号が変調もされるように、変調され、前記 テープ縁部センサ システムはさらに、 前記第4のフォトエミッタから前記第4の光信号の一部を受取るよう位置決めされ、受取った前記第4の光信号の前記一部に比例する第4の検出された信号を与える第4の光検出器と、 第4の開口を規定する第4のバッフルとを含み、前記第4のバッフルは前記第4のフォトエミッタと前記第4の光検出器との間に配置され、前記第4の開口は、前記第2のテープ縁部に、横方向テープ移動が検出される第4の領域を規定し、前記第2のテープ縁部は前記第4の光信号を部分的に遮断し、それによって、前記第4の開口とともに、前記第4の光検出器によって受取られる前記第4の光信号の前記一部における変動が横方向テープ移動によって少なくとも一部生じるように、前記第4の光検出器によって受取られる前記第4の光信号の前記一部を規定し、前記帰還システムは 、前 記第4のフォトエミッタおよび前記第4の光検出器に接続し、前記帰還システムは 、前 記第4の光検出器の変 調お よび前記第4の検出された信号のローパスフィルタ処理を与えて、ノイズおよび信号ドリフトからの干渉を最小限にする、請求項2に記載のテープ縁部センサシステム。
- 4前記第1のフォトエミッタ、前記第2のフォトエミッタ、前記第3のフォトエミッタおよび前記第4のフォトエミッタは、前記第1の光検出器、前記第2の光検出器、前記第3の光検出器および前記第4の光検出器からの出力が各々独立してローパスフィルタでフィルタ処理される状態で、同期して整流される、請求項3に記載のテープ縁部センサシステム。
- 5前記第1の光信号、前記第2の光信号、前記第3の光信号および前記第4の光信号は、各々独立して振幅変調される、請求項3に記載のテープ縁部センサシステム。
- 6前記第1の開口は、第1の長さおよび第1の幅を有して、概ね矩形であり、前記第1の長さは前記第1の幅より大きい、請求項1~5のいずれか1項に記載のテープ縁部センサシステム。
- 7前記第1の長さは、横方向テープ移動測定がテープ縁部粗さに実質的に反応しないように、前記記憶テープの移動の方向に実質的に平行に位置決めされる、請求項6に記載のテープ縁部センサシステム。
- 8前記第1の長さは、前記記憶テープの移動の方向に実質的に垂直に位置決めされる、請求項6に記載のテープ縁部センサシステム。
- 9前記帰還システムは、前記第1の光信号におけるドリフトを経時的に補償する、正規化されたスケーリングを与える、請求項1~8のいずれか1項に記載のテープ縁部センサシステム。
- 10前記第2の光検出器は前記安定部に対して前方位置に位置し、前記第4の光検出器は前記安定部に対して後方位置に位置する、請求項3に記載のテープ縁部センサシステム。
Independent claims10
29 paragraphs, as filed
The present invention relates to systems and methods for detecting lateral tape movement in an optical or magnetic storage tape drive.
Background of the invention The storage tape drive industry has used transmissive optical sensors to measure the dynamic behavior of tape edges traveling over tape feed subsystems. This technique is commonly used to estimate the lateral motion of the tape (LTM) at any position in the tape feed subsystem. However, the accuracy and sensitivity of this type of measurement is severely affected by some limitations. Such limitations include imperfections in the edge contours that appear inaccurately as LTMs, sensitivity limitations due to optical settings, and electromechanical and optical noise and drift contamination.
Lateral tape movement (LTM) becomes a problem in tape drives, especially as track pitches become smaller and smaller in new generation magnetic and optical drives. Data integrity must be maintained by servo-controlling the magnetic and optical read / write heads to trace track lateral movements typically better than 1/10 or l / 20 of the track pitch. As track pitches become smaller, for example in some optical tape drives, such as 320 nm, LTM measurements with accuracy up to microns or even tens of microns are no longer sufficient. Precise measurement of LTM is a valuable tool that can help tape path engineers to minimize LTM. Having a precision tape edge sensor in the product tape drive may be used to reduce LTM by applying feedforward servo control technology. Optical sensors such as photon probes and photointerruptors have been used to measure LTM, but they have been compared to the 10-20 nm required for newer, finer track pitches. It has the property of limiting their accuracy and resolution to unacceptable levels. An important parameter for optical tape edge detection is the sample length-the length of the tape edge that is "observed" or integrated at any given moment. Longer tape segments are measured to measure LTM without distortion due to tape edge roughness. If tape edge roughness with LTM will be measured, shorter segments will be measured. Unfortunately, photon probes and photointerruptors also have limited ability to change the sampling length of the tape.
Therefore, there is a need for an improved method of measuring lateral tape movement in a storage tape drive.
<p num="0005"> Outline of the invention The present invention solves one or more problems of the prior art by providing a tape edge sensor system for detecting lateral movement of a storage tape in a storage tape drive in at least one embodiment. The lateral tape movement is the movement of the storage tape in the vertical direction of the storage tape movement during the read / write operation. The tape edge sensor system is positioned to receive a first photoemitter that emits a first optical signal and a portion of the first optical signal, and is proportional to the portion of the first optical signal received. Includes a first photodetector that gives the detected signal of. The first photoemitter is modulated so that the first optical signal is also modulated. The first baffle defines the first aperture and the first baffle is located between the first photoemitter and the first photodetector. The first opening acts as an optical filter and defines a first region on the edge of the first tape where lateral tape movement is detected. The edge of the first tape partially blocks the first optical signal, thereby causing variations in the portion of the first signal received by the first photodetector, along with the first aperture, in the lateral tape. It defines a portion of the first optical signal received by the first photodetector so that it is at least partially generated by movement. The feedback system connects to the first photoemitter and the first photodetector and provides modulation of the first photoemitter and lowpass filtering of the first detected signal to interfere with noise and signal drift. To minimize.</p><p num="0006"> In another embodiment, a system is provided that compensates for the fluttering movement of the storage tape in the storage tape drive device. The system includes a first photoemitter that emits a first non-parallel light signal and a first photodetector that is positioned to receive a portion of the first non-parallel light signal. The first photoemitter is positioned close to the first tape side at the first tape edge, and the first photodetector is positioned close to the second tape side at the first edge. Will be done. First<u style="single">Photodetector</u>Outputs the first detected signal. The first non-parallel light signal is partially blocked by the storage tape at the edge of the first tape. The system further includes a second photoemitter that emits a second non-parallel light signal and a second photodetector that is positioned to receive a portion of the second non-parallel light signal. The second photoemitter is positioned close to the second tape side at the second tape edge, and the second photodetector is close to the first tape side at the second tape edge. Positioned. The second photodetector emits a second detection signal. The second non-parallel light signal is the second by the storage tape.<u style="single">2</u>Partially blocked at the edge of the tape. The system also allows the movement of the storage tape in a direction perpendicular to one tape side, the first photoemitter and the second photoemitter on the opposite side of the storage tape, and the first photodetector and second light. Includes a control component that combines the first and second detection signals so that they are compensated in the transfer function by positioning the detector on the opposite side of the storage tape.</p><p num="0007"> In another embodiment, a system is provided that compensates for the fluttering movement of the storage tape in the storage tape drive device. The system includes a photoemitter that emits an optical signal, a lens that forms the optical signal, and a first photodetector that is positioned close to the second side. The first part of the optical signal is directed to the first tape edge. The first photodetector is positioned close to the second side to receive the first portion of the optical signal. The first portion of the optical signal is partially blocked by the storage tape at the edge of the first tape.</p><p num="0008"> In yet another embodiment, a system for calibrating the tape edge sensor is provided. The system is mounted on a flat calibration board, a linear translation device that moves the flat calibration board in a linear direction, a monochromatic light source that emits an optical signal, a light detector, and a linear translation device. Includes a movable reflector that moves in unison with, a stationary reflector, and a beam splitter. The movable reflector moves in line with the flat calibration board. The beam splitter directs the first portion of the optical signal to the movable reflector and the second portion of the optical signal to the stationary reflector. The stationary reflector returns a third portion of the light signal towards the beam splitter, where the fourth portion of the light is directed at the photodetector. The movable reflector reflects a fifth portion of the optical signal towards the beam splitter, where the sixth portion of the optical signal is transmitted through the photodetector. The fourth part of the optical signal and the sixth part of the optical signal combine constructively and destructively to form an interference pattern as a function of the position of the plane calibration board. The interference pattern has a period that allows the determination of the distance traversed by the flat calibration substrate.</p><p num="0009"> It should be fully understood that embodiments and variations of the present invention provide many advantages. Tape edge sensor systems that increase detection sensitivity reduce noise and drift interference. The application of four sets of sensors allows information about the lateral movement of the storage tape to be transmitted to the tape head's tracking servo, which is used to reduce tracking errors by giving effective control signals. can do.</p><p num="0010"> An exemplary embodiment of the invention is better understood from the detailed description and accompanying drawings.</p>
<figref num="1A">A perspective view of a tape edge sensor system for detecting lateral tape movement in a storage tape drive using measurements at one to four positions is provided.</figref><figref num="1B">A side view of a tape edge sensor system for detecting lateral tape movement in a storage tape drive using measurements at one to four positions is given.</figref><figref num="2A">A schematic example of a baffle used in the tape edge sensor system of FIG. 1 is provided in which the long axis of the aperture is arranged parallel to the direction of movement of the tape during the read / write operation.</figref><figref num="2B">A schematic example of a baffle used in the system of FIG. 1 is given in which the long axis of the aperture is arranged perpendicular to the direction of movement of the tape during the read / write operation.</figref><figref num="3">A schematic diagram of the feedback system used to reduce noise in the edge tape sensor system of FIGS. 1A and 1B is given.</figref><figref num="4A">FIG. 5 is a perspective view of a tape edge sensor system for detecting lateral tape movement in a storage tape drive that compensates for fluttering (ie, Z-direction movement) in the storage tape.</figref><figref num="4B">It is a top view of the tape edge sensor system for detecting the lateral tape movement in a storage tape drive device which compensates for fluttering (that is, Z direction movement) in a storage tape.</figref><figref num="5">A graph demonstrating the effect of tape fluttering on LTM measurements is given.</figref><figref num="6">A schematic example of a system for detecting lateral tape movement in a storage tape drive, which monitors a single tape edge and determines the LTM using a parallel light source, is given.</figref><figref num="7A">FIG. 6 is a schematic side view of an improved system of FIG. 6 in which a lens is used to form an optical signal incident on the edge of the tape.</figref><figref num="7B">FIG. 6 is a schematic top view of an improved system of FIG. 6 that uses a lens to form an optical signal incident on the edge of the tape.</figref><figref num="8A">A schematic example is given of an elliptical irradiation pattern in which the long axis is parallel to the moving direction of the tape during the reading / writing operation and is incident on the edge of the storage tape.</figref><figref num="8B">A schematic example is given of an elliptical irradiation pattern in which the long axis is perpendicular to the moving direction of the tape during the reading / writing operation and is incident on the edge of the storage tape.</figref><figref num="9A">A schematic example of a system for detecting lateral tape movement in a storage tape drive, which monitors the top and bottom tape edges and determines the LTM using a parallel light source, is given.</figref><figref num="9B">It provides an improvement on the system in Figure 7A, where a third photodetector useful for normalization is utilized.</figref><figref num="10">A schematic diagram of the photolaser diode and photodetector configuration is given, where the photolaser diode provides a normalized output.</figref><figref num="11A">The configuration for using the normalized output of Fig. 10 is given.</figref><figref num="11B">The configuration for using the normalized output of Fig. 10 is given.</figref><figref num="11C">The configuration for using the normalized output of Fig. 10 is given.</figref><figref num="12">A schematic example of a calibration system for calibrating the linear region of the transfer function for a tape edge sensor system is given.</figref><figref num="13">A graph is given showing the overlap of the output of the calibration system of FIG. 12 with the linear region of the tape transfer function.</figref>
Description of the invention The currently preferred configurations, embodiments and methods of the invention are referred to herein in detail and they constitute the best mode of practice of the invention currently known to the inventor. The figure is not necessarily scaled. However, it is understood that the disclosed embodiments are merely exemplary of the invention, which may be implemented in various and alternative forms. Therefore, the particular details disclosed herein are not to be construed in a limited manner and merely teach those skilled in the art to use the invention in various ways and / or as a representative basis for any aspect of the invention. It should be interpreted as a representative basis for doing so.
Unless otherwise stated in the examples, all numerical quantities indicating the amount and / or use of a material or condition in this description are in the broadest scope of the invention. It is understood to be modified by the word "about".
Further, it is understood that the present invention is not limited to the specific embodiments and methods described below, as the specific components and / or conditions may of course vary. Moreover, the terms used herein are used solely for the purpose of describing particular embodiments of the invention and are not intended to be limiting in any aspect.
In addition, as used in the specification and claims, the singular forms "one / are (a, an)" and "that, the" must be clearly indicated that the context is not. For example, it should be noted that it contains multiple referents. For example, references to components in the singular are intended to include multiple components.
Refer to FIG. 1, the tape edge for detecting lateral tape movement (LTM) of the storage tape in the storage tape drive.<u style="single">Sensor</u>The system is given. System 10 is used to detect such lateral movement of the storage tape 12. The storage tape 12 includes a first tape edge 14, a second tape edge 16, a first tape side 18, and a second tape side 20. During operation, the tape 12 moves along direction d1 with lateral tape movement that occurs along direction d2. Typically, the lateral tape movement has a frequency of 0 to about 10 kHz. The system 10 includes a first photoemitter 22 that emits an optical signal S1 and a first photodetector 24 that is positioned to receive a portion of the first optical signal S1. The first photoemitter 22 is modulated so that the first optical signal is also modulated. The first photodetector 24 outputs a first detection signal proportional to a part of the first optical signal received by the first photodetector 24. In one improvement, the first photoemitter 22 is a laser diode, and / or the first photodetector 24 is a photodiode, a transparently optically coupled device. The first baffle 30 includes a first aperture 32 located between the first photoemitter 22 and the first photodetector 24. The first opening 32 defines, at the first tape edge 14, a first region 34 through which a portion of the first optical signal S1 is received by the first photodetector 24. The first tape edge 14 partially blocks the first optical signal (ie, the baffle 30 is located in the optical path of the first photodetector 24 and the first tape edge 14), thereby. A second photodetector 24 receives, along with the first aperture 32, such that at least some variation in the portion of the first signal received by the first photodetector 24 is caused by lateral tape movement. Specifies a part of the optical signal of 1.
System 10 further includes a feedback system 40 connected to a first photoemitter 22 and a first photodetector 24. The contour of tape 12 produces a signal, which is captured and registered as a tape transfer. It should be fully understood that there are at least two types of tape movement. For one movement, the tape 12 is in the direction d<sub>2</sub>It is a standing wave movement that moves up and down along. The other movement is a traveling wave movement in which the tape 12 twists and bends. When only one photoemitter / photodetector configuration is used, it is difficult to distinguish between these two types of movement. A variant corresponding to this problem is described below.
In one improvement, the feedback system 40 connects to a first photoemitter 22 and a first photodetector 24. The feedback system 40 also provides amplitude modulation of the first photoemitter 22 and lowpass filtering of the first detected signal to minimize interference from noise and signal drift. In one improvement, the feedback system 40 receives the first detection signal and adjusts the first optical signal so that the amplitude of the first detection signal is within the first average amplitude range. The feedback system 40 also outputs a first output signal that represents the deviation of the first tape edge from a predetermined value. Details of the modified example of the feedback system 40 are described in more detail below.
Figures 2A and 2B give schematic views of different aperture orientations. The aperture 32 operates as an optical filter in a modification of the present invention. Aperture 32 has two spatial dimensions l<sub>1</sub>And l<sub>2</sub>Characterized by. In Figure 2A, l<sub>1</sub>Is l<sub>2</sub>Larger, l<sub>1</sub>Is the direction of tape movement d<sub>1</sub>Aligned substantially parallel to. This configuration is somewhat less sensitive to edge tape damage and / or edge roughness during LTM measurements. In Figure 2B, l<sub>2</sub>Is l<sub>1</sub>Larger, l<sub>1</sub>Is the direction of tape movement d<sub>1</sub>Aligned substantially parallel to. This configuration is sensitive to edge tape damage and / or edge roughness during LTM measurements, thus providing a technique for assessing such damage.
In a variant of this embodiment, the system 10 is further positioned to receive a portion of the second photosignal S2 from the second photoemitter 42, the second photoemitter 42, and a second photodetector. Including 44. In one improvement, the second photoemitter 42 is a laser diode and / or the second<u style="single">2</u>The photodetector 44 is a photodiode. The second photoemitter 42 is modulated so that the second optical signal is also modulated. The second photodetector 44 is the second<u style="single">2</u>No. received by photodetector 44<u style="single">2</u>Outputs a second detected signal that is proportional to part of the optical signal of. The second baffle 46 includes a second aperture 48 and is located between the second photoemitter 42 and the second photodetector 44. The second opening 48 defines a second region 50 at the edge 16 of the second tape, and the second optical signal is a state in which the storage tape 12 blocks a part of the second optical signal. Received by the second photodetector 44 via the second region 50. In this variant, the top and bottom movements are adjusted, thereby giving better information about changes in the movement of the tape 12 (eg, tape edge damage or tape width that may fluctuate). In one improvement, the feedback system 40 connects to a second photoemitter 42 and a second photodetector 44. The feedback system 40 also provides amplitude modulation of the first photoemitter 42 and lowpass filtering of the second detected signal to minimize interference from noise and signal drift. The feedback system 40 receives the second detected signal amplitude and adjusts the second optical signal so that the second detected signal amplitude is within the second average amplitude range. The feedback system 40 also outputs a second output signal that represents the deviation of the second tape edge from a predetermined value.
Further, in a further variant of this embodiment, the system 10 further comprises two additional photoemitter / diode pairs as described above. Specifically, the system 10 further includes a third photoemitter 52 and a third photodetector 54 positioned to receive a third optical signal from the third photoemitter 52. In one improvement, the third photoemitter 52 is a laser diode and the third photodetector 54 is a photodiode. The third photoemitter 52 is modulated so that the third optical signal is also modulated. The third photodetector 54 outputs a third detection signal that is proportional to a portion of the third photosignal received by the third photodetector 54. The third baffle 56 includes a third aperture 58 and is located between the third photoemitter 52 and the third photodetector 54. The third opening 58 is the first A third region 60 is defined on the tape edge 14 of the tape, and the third optical signal is transmitted through the third region 60 in a state where the storage tape 12 blocks a part of the third optical signal. Received by the photodetector 54 of. In this variant, the system 10 further includes a fourth photoemitter 62 and a fourth photodetector 64 that is positioned to receive a fourth optical signal from the fourth photoemitter 62. The fourth photoemitter 62 is modulated so that the fourth optical signal is also modulated. The fourth photodetector 64 is a fourth photodetector.<u style="single">64</u>Outputs a fourth detection signal that is proportional to a portion of the fourth optical signal received by. In one improvement, the first<u style="single">4</u>Photoemitter 62 is a laser diode and / or<u style="single">4</u>The photodetector 64 is a photodiode. The fourth baffle 66 includes a fourth aperture 68 and is located between the fourth photoemitter 62 and the fourth photodetector 64. The fourth opening 68 defines the fourth region 70 at the second tape edge 16, and the fourth optical signal is the fourth optical signal, with the storage tape 12 blocking a portion of the fourth optical signal. Received by a fourth photodetector 64 through region 70 of four. In one improvement, stabilizers 72 are placed between pairs of photodetectors to stabilize the movement of the tape 12. In such an improvement, the tape head is positioned opposite the stabilizer 72. A third photoemitter 52 and a third photodetector 54 are also connected to the feedback system 40 as described above.
In one improvement, the feedback system 40 connects to a third photoemitter 52 and a third photodetector 54. The feedback system 40 also provides amplitude modulation of the third photoemitter 52 and lowpass filtering of the third detected signal to minimize interference from noise and signal drift. In one further improvement, the feedback system 40 receives a third detected signal and adjusts the third optical signal so that the amplitude of the third detected signal is within the third average amplitude range. The feedback system 40 also outputs a third output signal that represents the deviation of the first tape edge from a predetermined value. Similarly, a fourth photoemitter 62 and a fourth photodetector 64 are also connected to the feedback system 40 as described above, and the feedback system 40 is also amplitude modulated by the fourth photoemitter 62 and the fourth. Give low-pass filtering of the detected signal to minimize interference from noise and signal drift. In addition, in one further improvement, the feedback system 40 receives the fourth detected signal amplitude and adjusts the fourth optical signal so that the amplitude of the fourth detected signal is within the fourth average amplitude range. To. The feedback system 40 also outputs a fourth output signal that represents the deviation of the second tape edge from a predetermined value.
As mentioned above, tape movement may be characterized by both standing and traveling waves. The use of four photoemitter / photodetector pairs gives a better difference between these two movements than one or two photoemitter / photodetector pairs. For example, if a signal indicating tape movement is first observed by photodetectors 24 and 44 and then by photodetectors 54 and 64 after a certain time interval, it is concluded that the tape movement is that of a traveling wave. You may. In contrast, the continuous signal indicates that the tape movement is received simultaneously by the photodetectors 24, 44, 54 and 64. To some extent, these measurements are independent of tape edge damage.
In this variant, four photodetectors are placed on the side of the tape stabilizer with an associated opening. The use of the four photodetectors is as follows: the pair of photodetectors 24 and 44 is located in front of the stabilizer 72 at 68, and the pair of photodetectors 54 and 64 is relative to the stabilizer 72. The accuracy of LTM measurement is improved when it is located at the rear position 70. The LTM calculation is achieved via the following equation: A = LTM<sub>a</sub>+ N<sub>a</sub> B = LTM<sub>b b</sub>+ N<sub>b b</sub> C = LTM<sub>c</sub>+ N<sub>c</sub> D = LTM<sub>d</sub>+ N<sub>d</sub>In the equation, A, B, C, D are signals from photodetectors 24, 44, 54 and 64, respectively, and N<sub>a</sub>, N<sub>b b</sub>, N<sub>c</sub>And N<sub>d</sub>Is the non-coherent noise associated with each detector; LTM<sub>a</sub>, LTM<sub>b b</sub>, LTM<sub>c</sub>And LTM<sub>a</sub>Are lateral tape movements detected by photodetectors 24, 44, 54 and 64, respectively; LTM<sub>f</sub>Is a lateral tape movement at forward position 68; LTM<sub>b b</sub>Is the lateral tape movement at the rear position 70. LTM<sub>a</sub>= LTM<sub>b b</sub>= LTM<sub>f</sub>And LTM<sub>C</sub>Since = LTMd = LTMb, A + B = 2LTMf + Na + Nb is LTM<sub>f</sub>= (A + B) / 2+ (N<sub>a</sub>+ N<sub>b b</sub>) / 2. N<sub>a</sub>And N<sub>b b</sub>Is non-coherent noise, so (N<sub>a</sub>+ N<sub>b b</sub>) / 2 <N<sub>a</sub>Or N<sub>b b</sub>And C + D = 2LTM<sub>b b</sub>+ N<sub>c</sub>+ N<sub>d</sub>=> LTM<sub>b b</sub>= (C + D) / 2+ (N<sub>c</sub>+ N<sub>d</sub>) 2. N<sub>c</sub>And N<sub>d</sub>Is non-coherent noise, so (N<sub>c</sub>+ N<sub>d</sub>) / 2 <N<sub>c</sub>Or N<sub>d</sub>Is. Therefore, LTM<sub>f</sub>And LTM<sub>b b</sub>Are more accurate measurements at positions 68 and 70. In addition, if there is a momentary tilt on the tape due to the tape feed system or the stabilizer itself, the LTM<sub>f</sub>(t) LTM<sub>b b</sub>(t) and therefore the slope = LTMf (t) -LTM<sub>b b</sub>(t).
Different orientations of the openings are given with reference to FIGS. 1A, 1B, 2A and 2B. FIG. 2A provides an improvement in which the opening 32 is placed with its major axis parallel to the tape edge 14. This configuration allows an increase in the sensitivity of the photodetector 24 to edge displacement or movement due to the dark boundaries of the aperture on the optical path (ie, the maximum and minimum light detected by the detector. , Geometrically concentrated in the area near the edge of the tape). The application of this type of opening also has the advantage of reducing the contaminating effects of edge cutting or edge damage. A careful inspection of the open field of the tape edge at any moment, the momentary traveling wave of the tape (actual LTM) is precisely detected by the detector due to the change in emission that passes across the tape edge. However, it becomes clear that the traveling wave transfer of the tape edge having a wavelength less than the length of the aperture is averaged and therefore optically filtered. This phenomenon is highly desirable because the tape edge shape contours (including damaged edges) are of the traveling wave type, which is filtered and suppressed in this optical setting. ..
In a modification of this embodiment, the optical signal emitted from the photoemitter is modulated. For example, the applied current through the laser diode results in a modulation of the light intensity detected by the photodetector 24. Bandpass filtering and other signal processing are used. For example, the collector / emitter current of the detector is filtered by the carrier frequency of the photomodulated diode (that is, it demodulates the signal detected by the detector). The sensitivity of the detector to diode modulation is increased by reducing contamination caused by external optical and electrical noise. Typically, this carrier frequency is much higher (about 100kHz and above) than the typical frequency for LTMs (0-10kHz). This principle can be used in LTM detector settings as shown in FIG. The accuracy of the LTM registered by the transmission optical pair and aperture settings described above, as well as the further modulation and subsequent demodulation of the laser oscillated light as described herein, is significantly improved. Since the LTM does not fluctuate with respect to the optical movement detector settings described herein, the average value of the measured LTM is constant in the absence of component drift or other low frequency electromechanical and environmental disturbances. Should stay.
With reference to FIG. 3, a schematic illustration of the feedback system used in the lateral tape movement detection system described above is given. The feedback system uses Amplitude Modulation (AM) to minimize the effects of noise and drift during LTM detection. The LTM detection system 80 includes a photoemitter 82, a photodetector 84, and a baffle 86 that defines an aperture 88. The photoemitter 82, photodetector 84, baffle 86 and aperture 88 are configured as described above. The photoemitter 82 is an amplitude-modulated signal S.<sub>3</sub>Is propagated to the photodetector 84. The upper edge of the tape 12 partially blocks the optical signal, signal S'<sub>3</sub>Is received by the photodetector 84. The output of the photodetector 84 is filtered by a bandpass filter 90 centered on the frequency fc-the approximate frequency at which the optical signal is amplitude modulated. The output of the bandpass filter 90 is then passed through the full-wave rectifier 92, which gives an AC signal that converts negative values to positive values. The output of the full-wave rectifier 92 is given to the low-pass filters 94 and 96. The cutoff frequency fa of both lowpass filters 94 and 96 is lower than fc. The pass filter 94 gives an output signal indicating LTM, while the output of the low pass filter 96 is given to the adder circuit 98. A voltage is applied to the adder circuit 98 at the set point and compared with the output of the lowpass filter 96. The difference between the set point voltage and the signal from the lowpass filter 96 is determined and then given to the adder circuit 104. The frequency converter 106 feeds the AC signal to the adder circuit 104. Therefore, the adder circuit 104 outputs an AC signal to the square wave generator 108, and the square wave generator 108 outputs a square wave having a frequency of fc. The square wave is given to the integrator 110, which outputs a triangular wave of frequency fc. The frequency output by the square wave generator 108 is set to a value much higher (100 kHz or higher) than the typical frequency of lateral tape movement (0 to 10 kHz). The triangular wave passes through the bandpass filter 112 and is converted to a sine wave, which is used to drive the photoemitter 82. This improved feedback loop typically sets the LTM voltage to accommodate the tape blocking approximately half the area of the opening 88. This takes into account normalization of detector scaling and suppression of measurement variability due to temperature drift and external optical and electrical noise. The automatic gain control (AGC) loop presented in Figure 3 adjusts the amplitude of the modeled light at the diode level to ensure suppression of arbitrary component drift and other very low frequency disturbances.
In another embodiment, a tape edge sensor system is provided to minimize the effects of tape fluttering on the storage tape drive. 4A and 4B provide a schematic illustration of a system that compensates for the "fluttering" movement of the storage tape in the storage tape drive. Flapping movement is "z-axis"-tape surface and tape movement direction d<sub>1</sub>Vertical to-characterized by movement along. Prior art methods for tape edge detection do not use parallelized (parallel) light and / or have a light emission pattern and a detector sensitivity pattern that do not match. This fluctuates the transfer function of the sensor with tape flutter as described in Figure 5. In this embodiment, the tape flutter is placed in close proximity on the edge of the tape, but is compensated for by using two inverted photo interrupters.
Further with reference to FIGS. 4A and 4B, a system is provided that compensates for the "fluttering" movement of the storage tape in the storage tape drive. The storage tape 12 includes a first tape edge 14, a second tape edge 16, a first tape side 18, and a second tape side 20. The system 120 includes a first photoemitter 122 that emits a first non-parallel light signal S5, and a first photodetector 124. The first photoemitter 122 is positioned close to the first tape side 18, while the first photodetector 124 is close to the second tape side 20, of the first non-parallel light signal S5. Positioned to receive a portion. The first non-parallel light signal S5 is partially blocked by the storage tape 12 at the first tape edge 14. The system 120 further includes a second photoemitter 128 that emits a second non-parallel light signal S6, and a second photodetector 130. The second photoemitter 128 is positioned close to the second tape side 20, while the second photodetector 130 is positioned close to the first tape side 18. The second photodetector 130 receives a portion of the second non-parallel light signal S6. The second non-parallel light signal S6 is partially blocked by the storage tape at the first tape edge 14. First photoemitter 122 and second photoemitter on the other side of the storage tape<u style="single">128</u>, And the positioning of the first photodetector 124 and the second photodetector 130 on the opposite side of the storage tape is the storage tape in the direction perpendicular to the first tape side and the second tape side (that is, the Z direction). At least partially compensates for the movement of. The signals from the first photodetector 124 and the second photodetector 130 are components 12 so that the resulting signal is Z-independent. It is electronically combined (added) by 6. As the Z position of the tape fluctuates, the change in the slope of the transfer function of one photointerruptor has the same magnitude as the change in the slope of the second photointerruptor, but with the opposite sign, and their signals When added, the opposite tilts of the two sensors cancel each other out. In one improvement, the first photo emitter<u style="single">128</u>And the first photodetector 124 is contained within the photointerruptor 132, while the second photoemitter 122 and the second photodetector 130 are contained within the photointerruptor 134. The effectiveness of this solution is that the two photo interrupters have matching Z dependencies, that they are aligned vertically so that their transfer functions are aligned for proper offset, and that the tape. Requires that the Z-movement of the tape does not change significantly as it traverses the distance between the two sensors (approximately 3 mm or 4 mm).
With reference to FIGS. 6, 7A, 7B, 8A and 8B, an additional system for detecting lateral tape movement (LTM) of the storage tape in the storage tape drive is provided. This embodiment uses parallelized (parallel) light from a laser to provide a further solution to the Z-dependent problem. FIG. 6 provides a schematic diagram of a system for detecting lateral tape movement in a storage tape drive that monitors a single tape edge to determine LTM. The system 140 includes a photodiode 142, which is typically a laser diode, which emits a luminous flux 144, which is partially blocked by a first tape edge 14 of the tape 12 and a photodetector 146 (eg PIN). Received by the photodiode). The system 140 further includes a lens 148 that parallelizes the luminous flux 144 to form a parallel luminous flux 150. The parallel luminous flux 150 is aligned perpendicular to the surface of the tape 12 and falls on the side of the photodetector 146 facing the tape, producing a transfer function similar to the transfer function from the photointerruptor. However, in this case, the signal does not depend on the Z position of the tape. 7A and 7B are schematic views of the improvements of FIG. 6 that use a lens to shape the optical signal incident on the edge of the tape. FIG. 7A is a side view and FIG. 7B is a top view. In this improvement, a cylindrical lens 152 is used to adjust the optical footprint 154 of the optical signal at the tape edge 14 on the tape 12. By adding the cylindrical lens 152 to the optical path, the irradiation pattern can be reduced or magnified in only one direction on the surface of the tape as described above. Since the laser beam maintains parallelism in the lateral direction (LTM, or vertical in the figure above), the Z dependence of the sensor's transfer function is further minimized. 8A and 8B provide diagrams of achievable irradiation patterns. In FIG. 8A, the irradiation pattern 154 is an ellipse whose major axis is parallel to the tape edge. As mentioned above in the context of Figure 2A, this configuration has some impact on edge tape damage during LTM measurements. Hard to receive. In FIG. 8B, the irradiation pattern is also elliptical, but the long axis is perpendicular to the tape edge. As mentioned above in the context of FIG. 2B, this configuration is sensitive to edge tape damage during LTM measurements and therefore provides a technique for assessing such damage.
FIG. 9A provides a schematic diagram of a system for detecting lateral tape movement in a storage tape drive that monitors the top and bottom tape edges and determines the LTM using a parallel light source. The system 160 includes a photoemitter 162, which is typically a laser diode. The photoemitter 162 emits an optical signal 164, which is paralleled by a lens 166 used to parallelize the optical signal 164 to form a parallel optical signal 168. The first optical device 170 reflects the first portion 172 of the parallel light signal 168 toward the photodetector 174. The tape edge 14 blocks a portion of the first portion 172, thereby allowing evaluation of the LTM. The first optical device 170 further transmits the second portion 176 toward the second optical device 178. In one improvement, the first optical device<u style="single">170</u>Is a beam splitter. The second optical device 178 reflects the third portion 180 of the parallel light signal 168 toward the photodetector 182. The tape edge 16 blocks a portion of the third portion 180, thereby allowing evaluation of the LTM. In one improvement, the second optics 178 is either a mirror or a beam splitter. This variant allows the detection of LTM independent of the Z position of tape 12. FIG. 9B provides an improved version of the system of FIG. 9A. In this improvement, the system 160'reflects the third part 180 of the parallel light signal 168 towards the photodetector 182 and transmits the fourth part 188 towards the photodetector 190, a second optic. Includes device 178'. The output signal from the photodetector 190 allows normalization of the system 160 so that variations in the light intensity of the light signal 168 are compensated. The laser edge sensor of this embodiment is designed with a very small footprint that is useful for mounting in tight spaces around the tape path in either laboratory test fixtures or tape drive products. It is possible.
With reference to FIGS. 10 and 11A to 11C, variants are provided that reduce noise in a photodiode-derived signal. Such noise translates into error in LTM measurements. In order to reduce noise as much as possible in this type of sensor, the relative intensity noise in the laser beam is reduced as contributing to the measurement error by normalizing the signal. This can be done by dividing the signal indicating edge movement or LTM by the signal indicating the total output of the laser beam. Figure<u style="single">10</u>With reference to, the laser diode devices 192 and 194 emit an optical signal, which is received by the photodetectors PD1 and PD2, respectively. The optical signal is partially blocked by the top edge 14 and bottom edge 16 of the storage tape 12 as described above. The signals representing the overall ray output are LDPD1 and LDPD.<u style="single">2</u>It can be derived from the back detector of the laser diode device identified as. The detectors LDPD1 and LDPD2 receive a part of the light derived from the laser diode PD1 of the laser diode device 192 and the laser diode PD2 of the laser diode device 194. Figure<u style="single">11</u>A, figure<u style="single">11</u>B and figure<u style="single">11</u>C provides various configurations for using the outputs of LDPD1 and LDPD2. With reference to FIG. 11A, configurations for measuring apex and bottom edge signals are provided. In this configuration, the output of PD1 and the amplified output LDPD1 are given to the voltage divider 198.<u style="single">LD</u>Amplification of PD1 is achieved via amplifier 200. Similarly, the output of PD2 and the amplified output LDPD2 are given to the voltage divider 202.<u style="single">LD</u>Amplification of PD2 is achieved via amplifier 204. A configuration for measuring LTM directly is provided with reference to Figure 11B. In this configuration, the outputs of PD1 and PD2 are given to the voltage adder 204. The output of the voltage adder 204 and the amplified output LDPD1 are given to the voltage divider 206. Amplification of LDPD1 is achieved via amplifier 208. The configuration for the tape width is given with reference to figure 11C. In this configuration, the outputs of PD1 and PD2 are given to the differential amplifier 210. The output of the differential amplifier 210 and the amplified output LDPD1 are given to the voltage divider 212. Amplification of LDPD1 is achieved via amplifier 214. The method associated with FIGS. 11A-11C allows the laser output variation to be compensated for in the final measurement, with signal normalization achieved using an analog electronic circuit or digital signal processor after digitization of the signal. To.
A system for calibrating the tape edge sensor is provided with reference to FIG. To achieve a high level of measurement accuracy, the tape edge sensor requires precise calibration. The most important part of the sensor's transfer function is near its midpoint-the linear measurement region. A calibration method that precisely measures the tape movement at the same time as the output signal of the edge sensor gives the desired information: the slope of the transfer function in the measurement area. The calibration system 220 aligns a flat calibration board 222 (eg, a sample of small tape material), and a flat calibration board.<sub>7</sub>Includes a linear translation device 224 that moves to. Typically, the linear translation device 224 is a voice coil motor driven by a sinusoidal signal from a low frequency (10 Hz) oscillator 226 to move a sample of small tape material. The light source 230 and the photodetector 232 are part of the tape edge sensor 228. The light source 230 emits an optical signal, which is received by the photodetector 232, partly blocked by the flat substrate 222. The flat calibration board 222 is positioned on the tape edge sensor 228 so that the central region of the transfer function of the tape edge sensor 228 is swept by the linear translation device 224. A movable reflector 234 that moves in line with the flat calibration board 222 is attached to the linear translation device 224. The system 220 further includes a laser 236 that emits a monochromatic light signal 238. The cube beam splitter 240 reflects the first portion 242 of the optical signal towards the movable reflector 234 and transmits the second portion 244 of the optical signal towards the stationary reflector 246. The stationary reflector 246 returns a third portion 248 of the optical signal towards the beam splitter 240, where a fourth portion 250 of light is directed at the photodetector 252. In one improvement, both the movable reflector 234 and the stationary reflector are corner cube reflectors. The movable reflector 234 returns a fifth portion 254 of the optical signal towards the beam splitter 240, where the sixth portion 256 of the optical signal is transmitted through the photodetector 252 (eg, a photodiode). The fourth part 250 of the optical signal and the sixth part 256 of the optical signal combine constructively and destructively to form an interferometer signal (eg, an interferometric pattern) as a function of the position of the plane calibration substrate 222. .. The interference pattern has a period that allows the determination of the distance traversed by the flat calibration substrate. The resulting interferometer signal from photodetector 252 is a sine wave whose period represents the movement of the linear translation device 224, which is equal to 1/2 (λ / 2) the wavelength of the laser. For 650nm (red) laser diodes This period represents 325 nm. Figure<u style="single">13</u>Gives an example of the output of the calibration system overlaid on the graph of the transfer function of the edge sensor. The slope in the linear region is evaluated from the distance between points P1 and P2 by counting the number of cycles that intersect the transfer function. The slope of the transfer function (volts / nanometers) is calculated from the signal produced by this calibration method. To achieve high absolute accuracy, the wavelength of the laser must be known accurately, for example by measuring it with an optical spectrometer.
Although embodiments of the present invention have been shown and described, it is not intended that these embodiments indicate and describe all possible forms of the invention. Rather, it is understood that the wording used herein is a descriptive wording, not a limitation, and that various modifications may be made without departing from the spirit and scope of the invention.
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Every citation, both ways
| Document | Relation | Office |
|---|---|---|
| JP2005129212A | Cites | Japan |
| JP09318349A | Cites | Japan |
| JP05332721A | Cites | Japan |
| JP2001208533A | Cites | Japan |
| JP54076219A | Cites | Japan |
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Priority claims9
| Document | Office | Kind | Date |
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| 13531875 | United States of America | – | |
| 201213531875 | United States of America | A | |
| 201213531875 | United States of America | A | |
| 2013045629 | United States of America | W | |
| 2013045629 | United States of America | W | |
| 13531875 | – | – | – |
| US201213531875 | – | – | – |
| US2013045629 | – | – | – |
| WO2013US45629 | – | – | – |
Members14
| Document | Office | Kind | |
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| US2013342930A1 | United States of America | A1 | |
| WO2014004096A1 | World Intellectual Property Organization (WIPO) | A1 | |
| US8760786B2 | United States of America | B2 | |
| AU2013280927A1 | Australia | A1 | |
| CN104272385A | China | A | |
| EP2864984A1 | European Patent Office (EPO) | A1 | |
| JP2015526707A | Japan | A | |
| HK1204137A | Hong Kong, China | A | |
| HK1204137A1 | Hong Kong, China | A1 | |
| NZ629024A | New Zealand | A | |
| CN104272385B | China | B | |
| JP6190880B2This record | Japan | B2 | |
| EP2864984B1 | European Patent Office (EPO) | B1 | |
| AU2013280927B2 | Australia | B2 |
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Numbers
- Publication
- 6190880
- Publication, DOCDB
- 6190880
- Publication, EPODOC
- JP6190880B
- Application
- 2015518458
- Application, DOCDB
- 2015518458
- Application, EPODOC
- JP20150518458
Titles2
- Japanese
- 横方向テープ移動検出器
- English
- Lateral tape movement detector
Classification
- CPC, 8
- G11B15/602
- G11B5/584
- G11B20/10388
- G11B2220/90
- B65H23/0216
- B65H2553/412
- B65H2701/11332
- B65H2701/1315
- IPC, 2
- G01B11 00
- G11B5 58
