High Data Transfer Rate Research Articles

C109 ディスク回転流を利用した光ディスクドライブの冷却技術

Recently, data transfer rates of optical disc drives have been dramatically increasing. To obtain the high data transfer rates, disc rotation speed and laser power also need to be increased. Therefore, to develop the next generation optical disc drives effectively, enhanced cooling system of the optical pick-up unit which includes the laser diode is indispensable. The cooling performance of the pick-up unit is directly influenced by the inside airflow induced by the disc rotation. Tb maximize the effect of the airflow around the pick-up unit, we applied the combination of PIV (Particle Image Velocimetry) and CFD (Computational Fluid Dynamics) simulation. It was made clear that the tray opening near the pick-up unit increased the cooling performance effectively.

B242 ディスク回転流を利用した光ディスクドライブの冷却技術(エレクトロニクス機器・デバイスのサーマルマネージメント3)

Recently, data transfer rates of optical disc drives have been dramatically increasing. To obtain the high data transfer rates, disc rotation speed and laser power also need to be increased. Therefore, to develop the next generation optical disc drives effectively, enhanced cooling system of the optical pick-up unit which includes the laser diode is indispensable. The cooling performance of the pick-up unit is directly influenced by the inside air-flow induced by the disc rotation. To maximize the effect of the air-flow around the pick-up unit, we applied the combination of PIV (Particle Image Velocimetry) and CFD (Computational Fluid Dynamics) simulation. It was made clear that making the opening near the pick-up unit could increase the cooling performance of the optical disc drive very effectively.

Development of an Air Gap Servo System for High Data Transfer Rate Near Field Optical Recording

This paper describes development of a bi-axial actuator-based air gap servo system for a near field optical recording system using a blue laser and a solid immersion lens (SIL). We first present a new pull-in procedure ensuring smooth air gap servo start-up without lens-disc collision. Furthermore, a memory-loop control technique has been employed to realize a high-speed air gap servo system guaranteeing a high data transfer rate.

Signal processing for multitrack digital data storage

Using a multitrack format in both optical and magnetic data storage applications yields important improvements in system performance, including higher data density and higher data transfer rates. However, the full advantage in data density can be achieved only through the use of joint equalization and joint detection. This paper addresses the complexity of implementing these functions and proposes a transform domain equalization architecture and a reduced-complexity detection method based on a breadth first search of a one-dimensional time-varying representation of a two-dimensional target response. With this method, the complexity of joint equalization and joint detection is not unreasonably greater than that of existing single-track systems and should be feasible for implementation with emerging integrated circuit technologies.

Optical Flying Head의 Air Bearing Surface 형상 최적 설계

The systems with probe and SIL(Solid Immersion Lens) mechanisms have been researched as the technology to perform NFR(Near Field Recording). Most of them use the flying head mechanism to accomplish high recording density and fast data transfer rate. In this paper, ABS shape of flying head was optimized with the object of securing the maximum compliance ability of OFH. We suggest low different optimization processes to predict the static flying characteristics for the OFH. Two different approximation methods, regression analysis and back propagation neural network were used. And we compared the result of directly connected(between CAE and optimizer) method and two approximated optimization results. Design Optimization Tool(DOT) and were used as the optimizers.

光ディスク装置へのフィードフォワード制御の適用

A high-speed and precise focusing/tracking servo system is indispensable for developing a HDTV optical disk camera-recorder. This system is needed for higher data transfer rate and recording density. In this work, we adopted a feedforward control employing the Zero Phase Error Tracking method for the focusing/tracking servo system, and this method reduced residual focusing/tracking errors compared with a feedback system. In addition, we confirmed that the method makes possible obtaining stable recordings and reproduces signals in optical disk systems with the high data transfer rate needed for broadcast use.

Estimation of Feasibility for 100 Mbps High Data-Transfer Rate on an Optical Disk with High Areal Density Using Multilevel Recording

We developed a method and a new read-out tester to estimate the feasibility of achieving a high data-transfer rate in the case of multilevel recording. We introduced a second harmonic generation (SHG) laser as a light source and a developed preamplifier having the characteristics of low noise and a wide bandwidth into the tester. We also demonstrated the feasibility of 100 Mbps data transfer using a read only memory (ROM) disk with areal densities corresponding to 40 Gbit/in2 and 100 Gbit/in2 using single-carrier independent pit-edge recording/two-dimensional partial response maximum likelihood (SCIPER/2DPRML) format.

A partial response read channel for two dimensional optical data storage

This paper describes an architecture for a read channel which can be used to recover data from a multi-track optical medium. The multi-track format allows for a higher density of data storage as well as a higher data transfer rate for applications such as high density DVDs. The proposed channel is based on a 2D partial response over a hexagonal lattice and employs a 2D nonlinear equalizer and 2D data detection. Bit error measurements based on sampled data from a prototype disc and optics, and offline software read channel are presented and show satisfactory performance.

A Magnetic Coil Suitable for Magneto-Optical Recording with a Large Working Distance

A first surface magneto-optical (MO) system has a high storage density and a high data-transfer rate. The high-density recording is achieved using a blue laser and lenses that have a high numerical aperture (more than 0.85) and that are integrated with a magnetic-field modulation coil. If the working distance is more than 30 µm, the optical head can be controlled by using a mechanical actuator, for which many existing technologies are available. We have developed a magnetic coil suitable for working distances of up to 30 µm. First, we analyzed the relationship between the properties of a magnetic layer and a magnetic field and then from our analysis derived three design concepts. We then designed a magnetic coil with a fan-shaped magnetic layer composed of stick-shaped magnetic bodies and heat sinks; testing showed that it can be driven at a data transfer rate of 80 Mbps and that it has a wide temperature margin.

Quantitative image quality evaluation of pixel-binning in a flat-panel detector for x-ray fluoroscopy.

X-ray fluoroscopy places stringent design requirements on new flat-panel (FP) detectors, requiring both low-noise electronics and high data transfer rates. Pixel-binning, wherein data from more that one detector pixel are collected simultaneously, not only lowers the data transfer rate but also increases x-ray counts and pixel signal-to-noise ratio (SNR). In this study, we quantitatively assessed image quality of image sequences from four acquisition methods; no-binning and three types of binning; in synthetic images using a clinically relevant task of detecting an extended guidewire in a four-alternative forced-choice paradigm. Binning methods were conventional data-line (D) and gate-line (G) binning, and a novel method in which alternate frames in an image sequence used D and G binning. Two detector orientations placed the data lines either parallel or perpendicular to the guide wire. At a low exposure of 0.6 microR (1.548 x 10(-10) C/kg) per frame, irrespective of detector orientation, D binning with its reduced electronic noise was significantly (p<0.1) better than the other acquisition methods. On average, alternate binning performed better than G binning. At a higher exposure of 4.0 microR (10.32 x 10(-10) C/kg) per frame, with data lines parallel to the guidewire, detection with D binning was significantly (p<0.1) better than G binning. However, with data lines perpendicular to the guidewire, G binning was significantly (p<0.1) better than D binning because the partial area effect was reduced. Alternate binning was the best binning method when results were averaged over both orientations, and it was as good as the best binning method at either orientation. In addition, at low and high exposures, alternate binning gave a temporally fused image with a smooth guidewire, an important image quality feature not assessed in a detection experiment. While at high exposure, detection with no binning was as good, or better, than the best binning method, it might be impractical at fluoroscopy imaging rates. A computational observer model based on signal detection theory successfully fit data and was used to predict effects of similar acquisition methods. Results from this study suggest the use of exposure-dependent detector binning in fluoroscopy that switches between D binning and alternate binning at low and high exposures, respectively.

High speed sub-micron bit detection using tapered aperture mounted optical slider flying above a patterned metal medium

Rapid advances in the development of the digital network society have necessitated both large capacity and higher data transfer rate for every type of digital storage equipment. Proximity optical recording based on the near-field interaction principle promises to provide breakthroughs in overcoming rigid optical diffraction limits and wave length shortening limits. We have previously presented a compact optical head assembly consisting of a combination of a pyramidal hole processed silicon slider and light-wave guide combined suspension. Attaining higher recording density requires both a much smaller sized aperture and a highly efficient laser power delivery mechanism. To satisfy these requirements, we have introduced a planar lens and tapered aperture processed optical slider, delivering laser power through a single mode optical fiber, and we have demonstrated sub-micron size (150–200 nm-long) bit signals at more than a 10 MHz frequency band.

Recordable Digital Versatile Disc for High Data Transfer Rate Recording

We studied the characteristics of the 4.7 GB recordable digital versatile disc (DVD-R) for a high data transfer rate higher than 44 Mbps. Using simulation, analytical pulse sequence and atomic force microscopy (AFM) measurement, we analyzed the thermal interference. We also used originally synthesized dye with low thermal interference and realized good recording characteristics with jitter values of around 8% at 66 Mbps recording and 11% at 89 Mbps recording.

Feed-Forward Tracking Servo System for High-Data-Rate Optical Recording

A high-speed and highly precise track-following control system for high-data-rate optical recording is proposed. We are developing an optical disk camera-recorder to record high-definition television signals for collecting broadcast program materials. This system must have both a high data transfer rate of more than 100 Mbps and a large recording capacity. That requires high-speed rotation of the optical disk and highly-precise optical head control for tracking on narrow-pitch disks. To meet these requirements, we propose a new tracking control method consisting of a feedback controller and a feed-forward controller that employs the zero phase error tracking method. Simulation results show that the feed-forward controller suppresses tracking error. Suppression of tracking error is also shown by experiments using an optical disk tester composed of a blue-violet laser and a high-density optical disk controlled by an experimental device that implements the optimized algorithm of this control method at high speed.

Optical Properties and Crystallization Characteristics of Ge-Doped Sb70Te30 Phase Change Recording Film

Eutectic Sb70Te30 fast-growth material is one of the promising candidates for high data transfer rate recording. However, it also shows the disadvantage of poor thermal stability. Germanium, with a high value of glass transition temperature, is expected to play the role of thermal stabilizer. It was found that the effect of Ge doping on reflectivity difference between as-deposited and annealed states is not significant. However, the addition of Ge element into Sb70Te30 can reduce the initialization or erasure power, and increase the stability of the phase change recording media at room temperature at the same time. Unfortunately, doping Ge element would also slow down the crystallization speed of eutectic Sb70Te30 recording film.

Resource-Based Striping: An Efficient Striping Strategy for Video Servers Using Heterogeneous Disk-Subsystems

In building a large-scale video server, it is highly desirable to use heterogeneous disk-subsystems for the following reasons. First, existing disks may fail, especially in an environment with a large number of disks, enforcing the use of new disks. Second, for a scalable server, to cope with the increasing demand of customers, new disks may be needed to increase the server's storage capacity and throughput. With rapid advances in the performance of disks, the newly added disks generally have a higher data transfer rate and a larger storage capacity than the disks originally in the system. In this paper, we propose a novel striping scheme, termed as resource-based striping (RBS), for video servers built on heterogeneous disks. RBS combines the techniques of wide striping and narrow striping so that it can obtain the optimal stripe allocation and efficiently utilize both the I/O bandwidth and storage capacity of all disks. RBS is suitable for applications whose files are not updated frequently, such as course-on-demand and movie-on-demand. We examine the performance of RBS via simulation experiments. Our results show that RBS greatly outperforms the conventional striping schemes proposed for video servers with heterogeneous or homogeneous disks, in terms of the number of simultaneous streams supported and the number of files that can be stored.

A novel wideband antenna package design with a compact spatial‐notch filter for wireless applications

AbstractThis paper presents a compact package, comprising a wideband antenna with a compact spatial‐notch filter, useful for RF applications requiring a high rate of data transfer. Fractal concepts are employed to help reduce the package to almost half the normal size, and to realize a much sharper band‐stop than would be possible with a conventional filter. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 455–460, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10637

Improvement of dynamic characteristics for optical pickup actuator using sensitivity analysis

The disk rotation speed of optical disk drives (ODD) has been increasing rapidly to achieve high data transfer rates. High servo bandwidths for focusing and tracking actuator are required to follow dynamic disturbance by high rotation speed in ODD. However, the servo bandwidth is significantly limited by some vibration modes which are induced by the flexibility of the moving part. In this work, the vibration modes affecting the bandwidth of actuators are shifted to high frequency range and suppressed by modifying the FE model which is used to analyze the motion of the actuator. Some local dimensions of the lens holder, which is included in the moving part, are selected as design variables to increase the stiffness without changing the material properties. Selected modal frequencies of the moving part are raised about 10%, while the performances of actuator such as DC and AC sensitivities are hardly affected by the modification.

A high density and high data transfer rate flexible disk drive for insertion to the PCMCIA type-II slot

We have developed a new small, flexible magnetic-disk recording system which has the largest areal density (672 Mbit/sqin) in FDD formats and a 18 Mbit/sec maximum user data transfer rate. This is a new card size flexible disk drive (CFDD) format using a 1.75-inch disk on which 146 Mbytes of data can be stored.

High-Throughput GaP Microprobe Array having Uniform Aperture Size Distribution for Near-Field Optical Memory

The GaP metal-aperture microprobe array has been studied for application to the parallel near-field optical array head of high memory capacity and fast data transfer rate. The fabrication of such an array having uniform aperture size distribution was realized using a low-temperature etching solution of HF:HNO3 and the careful control of ion-milling parameters. After the flat-tip formation by the wet etching method and the aperture formation by the ion-milling process, GaP microprobes of more than 90% in the array show an acceptable size distribution in the range of 150±30 nm. It was observed from the near field scanning optical microscope (NSOM) observation that tiny apertures are formed on the top of the microprobes and light comes out only from the aperture. The light penetrated through the 200 nm aperture shows approximately 170 nm beam size in full width half maximum (FWHM). Due to the high refractive index, the cut-off diameter of GaP microprobes decreases to approximately 200 nm, resulting in improved optical throughput with more than 100 times increment compared with that of the conventional optical fiber probe. For the microprobe having 150 nm aperture, 1.25% optical throughput was realized in this research. The design concept for the semiconductor microprobe array having high optical throughput with uniform aperture size distribution has been proved experimentally.

Signal-to-noise ratio of nondestructive photocurrent-detection readout in near-field photochromic memory: theoretical study

The signal-to-noise ratio (SNR) and possible data-transfer rate of nondestructive photocurrent-detection readout in near-field photochromic memory were calculated theoretically. The photocurrent-detection readout provided a much higher SNR and a higher data-transfer rate than those of conventional transmittance-detection readout. The SNR of the photocurrent-detection readout was dependent on the electric field applied to the medium and the potential barrier height between the photochromic recording layer and the photoabsorbing layer. A sufficient SNR was obtained under the conditions of an electric field of 2.5 V/m and a potential barrier height &lt;0.4 eV in land area. Photocurrent-detection readout is a promising method to achieve high SNR, high data-transfer rate, and ultrahigh recording density with nondestructive-readout capability.