磁盘系统中磁头定位的光学方法

本文报导了磁盘系统中磁头定位的一种新的光学方法。为了提高磁头定位的精度,研究过几种不使用伺服盘的磁头定位方法,但由于记录在同一数据面上的磁头定位信号与数据信号之间产生干扰,这些方法至今都不成功。在本文说明的新方法中,磁头能用一个光学检测的位置信号定位在磁盘盘面上,同时又不扰乱磁盘系统的运行。 本文研究了一种磁盘与磁头的独特结构。它在铝基片的阳极氧化层上着色再在其上面形成一种磁膜,从而构成描述数据磁道位置的光学图形。在Winchester型铁氧体磁头中间轨道的一个孔中埋置着三条光纤维,盘面上的光学图形由这三条光纤维读出。 用光学方法从旋转的磁盘上检测出一个稳定的位置信号,用这个信号组成一个简单的伺服回路,使磁头能够以±3μm精度定位。曾经发现潜在的精度为±0.7μm。     

预（光）刻伺服录写装置光记录系统设计

将光盘驱动器高道密度记录技术应用于磁盘驱动器，对于大幅度提高磁盘驱动器的容量具有非常重要的意义。预（光）刻伺服录写装置便是开发大容量磁盘驱动器的一种高精尖技术设各。本文主要讨论预（光）刻伺服录写装置光记录系统设计。该系统中以完成６３６０ＴＰＩ磁盘的刻录。     

磁盘伺服图形光刻机主轴稳速系统设计

叙述了影响磁盘伺服图形光刻机主轴转速误差主要来源，分析了主轴稳速系统是实现光刻机均匀刻录不可缺少的重要环节，提出了提高主轴稳速精度具体设计方案。     

1001机磁盘存贮器和研制情况

1001磁盘存贮器是由一台立式磁盘、读写放大器和伺服驱动电路及控制逻辑等几部分组成。其中读写放大器和伺服驱动电路直接安放在磁盘机箱内,整台磁盘体积为750×690×1190毫米~3。 1001磁盘采用6片盘组,共有十个记录面,盘片直径为380毫米,内径为160毫米,厚度为2毫米,基体采用硬铝,在表面甩涂一层三氧化二铁胶,厚度控制在3—4微米,磁胶的Hc约320奥斯特,Br约1000高斯,片与片之间的间隔约15毫米。     

为你的信息加密

数字时代，人们开始习惯将自己的信息保存为二进制数据．并且将光磁和全息图像当作载体来保存这些二进制数据．这样做的好处是，可以让数据保存的时间更长。与纸张和照片相比，用磁盘和闪存体保存数据可以让数据保存的时间更长，但是这样做所带来的缺点是：将存储在光磁等存储介质上的数据很容易被非法用户读取，在这样的背景下，信息加密系统应运而生。     

磁浆和磁涂层的制备

磁盘存储是由磁头靠空气动力在盘上面浮动实现记录信息的。磁盘片上有很薄的磁涂层,一般说来,磁头在磁盘上起落时,对盘片总有一个暂短的接触过程。因此,磁盘要求盘片的磁涂层具有优良的机械强度,如耐摩、耐冲击和高硬度等。同时,作为记录层,磁涂层必须有优良的磁性能。磁盘对盘片上述的性能要求,便是磁涂层原料──磁浆的配方选择,制备和深层制备中,有关工艺指标确定的基本出发点,     

磁盘伺服图形光刻机主轴稳速系统设计

该文叙述了影响磁盘伺服图形光刻机主轴转速误差的主要来源,分析了主轴稳速系统是实现光刻机均匀刻录不可缺少的重要环节,提出了提高主轴稳速精度具体设计方案。     

HI-MD，Sony新利器

早在HI-MD还未问世的时候我们就通过各种渠道了解到它的目标是在保持现有MD光磁盘的光学系统的同时，提高面记录密度，进而提高每张盘的记录容量。HI-MD光磁盘的直径为64.8mm，光源波长为780nm，物镜开口数为0.45，与现有MD光磁盘基本相同。现在HI-MD已经实实在在摆在我们面前，让我们仔细地看看它的技术特点。     

刚柔相济——光技术改进硬盘驱动器特性

前不久,Quinta公司推出一种新的磁盘驱动技术。这一技术不仅改变了传统驱动器的可靠性,而且进一步提高了传统驱动器的存储容量,从而大幅度降低了它们的产品价格。 Quinta公司这一名为OAW(光辅助Winchester)的磁盘驱动技术改变了传统驱动器记录数据的方法,即它把光技术与Winchester风格的高速扫描磁     

磁光特性测试系统的软件设计

磁光特性测试仪是用来测量磁光盘记录介质的磁光参数的仪器.详细讨论了在Windows操作系统下磁光特性测试系统的软件设计,简要介绍了磁光特性测试系统的测试原理.     

Tracking servo method using reflective optical filter for holographic data storage system

Holographic data storage system is one of the next-generation data storage systems and is characterized by its high storage density and fast data transfer rate. However, holographic data storage systems are very sensitive to disturbances that affect the position of the media. Therefore, tracking servo control is needed to ensure a good performance of the system even if disturbances occur, such as eccentricity of the disk and external shock. In our previous researches on tracking servo methods, we used additional beams or recorded servo track images with data pages to record additional gratings with data pages. Therefore, the recording density may be reduced and the system may be complicated. In addition, the performance of the system may be compromised by cross-talk noise caused between the reference beams and additional beams. In this paper, we propose a tracking servo method using the residual beam, which is reflected by the reflective optical filter. This method does not require recording supplementary gratings or use additional beams, and only needs to record data pages. The residual beam is retrieved with desired retrieved beam by the reference beam and wasted during the retrieving process. We first constructed a holographic data storage system and designed a reflective optical filter to detect tracking error signals. After detecting the tracking error signals, a tracking servo controller using a lead-lag compensator was incorporated to reduce the tracking error signals. The performance of the designed controller was verified by simulated and experimental results. Finally, the performance of the tracking servo method was investigated by comparing the retrieved data images.     

Robust design of a microactuator for HDD head positioning

With rapid growth in areal recording density of hard disk drive (HDD), ultra-high precise head positioning and higher servo bandwidth are required. Dual-stage actuation system using MEMS actuator has been considered as one promising precise positioning solution. The microacatuator we designed has a low in-plane resonant frequency, which limits the servo bandwidth and needs compensation by servo control system. However, this resonant frequency may shift from its mean value during MEMS fabrication process. This shift adds difficulty to effective compensation for servo control. In this paper, a robust solution is proposed to minimize microactuator’s resonant frequency shift so that its first resonance frequency is insensitive to the effects of sources of processing variations and then effective compensation for high servo bandwidth can be achieved.     

Generation of fuzzy rules and learning algorithm for servo control in holographic data storage system

Today many media of information storage device are formed as disks. Hence, next generation removable data storage media are shaped as disk types too. The holographic data storage system also uses a disk type photopolymer media. And then, holographic data storage system is most advanced optical memory system. Tracking servo and tilt servo control are very important research in holographic data storage system. In this paper, we propose intelligent servo control by fuzzy rules in holographic data storage system. Hence, we have found pattern of tilt servo control in holographic data storage system through fuzzy system and genetic algorithm. Fuzzy rules were generated by genetic algorithm for controlling tilt servo. Therefore, we control tilt servo using fuzzy rules in holographic data storage system. Consequently, Image input–output patterns of tilt servo control was found by intelligence algorithm in holographic data storage system.     

Linear actuator for precise track following

A new air bearing linear actuator with a Voice Coil Motor (VCM) was investigated for a precise head track following in an Hard Disk Drive (HDD) magnetic recording tester system. The actuator has a servo bandwidth of two times as wide as that of a conventional HDD, due to a high stiffness without any friction. A low-pass filter was introduced to precisely monitor the step response behavior by reducing the relatively large noise of the used optical fiber sensor. The effect of the low-pass filter was investigated comparing with the other method. Track following accuracy was also tested by using a conventional 2.5-inch hard disk drive. The head installed on the actuator could follow on a track by using Position Error Signal (PES) from the servo pattern. When a Double Metal In Gap (D-MIG) head of 4 μm track-width was loaded on a disk rotating at 4200rpm, the tracking error could be compressed down to one-twentieth of the track-width. The tested system did not show any azimuth error of head-tracking due to the linear motion. In conclusion, the air-bearing linear actuator is suitable for a precise track following mechanism of a spin-stand tester for an HDD system.     

Dynamics simulation of MEMS device embedded hard disk drive systems

Currently, hard disk drives (HDD) use rotating disks to store digital data and magnetic recording heads are flying on the disk to read/write data. The recording heads are mounted on a slider–suspension assembly, which makes heads move from one track to another on the disk. The heads movement is controlled by close-loop feedback servo systems. It is well known that dynamic behaviors of head–slider–suspension-assembly (HSA) systems are of great influence on the track per inch capacity of HDD [1, 2]. As the problem is structurally complex, it is usually investigated using experimental methods or finite element simulation models [3]. Furthermore, the dual-stage servo system has been commonly considered as one promising solution to increase the servo bandwidth of the recording positioning system for high TPI HDDS. In particular, MEMS device embedded systems are superior to others in batch-fabrication. However, this dual-stage system has also resulted in more difficulties in predicting HDD dynamic performance. This paper presents the study of the problem using the macromodeling simulation approach. It applies efficient FEM based sub-structuring syntheses (SSS) [4] and fast boundary element method (BEM) approaches incorporated with system dynamics technology to investigate the dynamic characteristics of MEMS actuator embedded HSA systems for HDD.This research is funded by the Agency for Science, Technology and Research of Singapore, Strategic Research Program. Also, the authors would like to thanks Miss Jia Wenhui, who is a Research Student with ECE Department at National University of Singapore, Mr. Lim Boon Buan, the former research engineer with Data Storage Institute, for the MEMS actuator modeling and analytical work.     

Tracking servo method for holographic data storage using discrete pre-patterns

Page-oriented holographic data storage (HDS) is very sensitive to disturbances that affect the position of the recording medium. Accordingly, a more precise tracking servo is required for the recording process, and is also crucial for achieving high storage density. A compensation method is therefore essential for HDS recording. In this paper, we suggest some discrete pre-patterns for the tracking servo used in the recording process. This method is motivated by a tracking servo technique for a hard disk drive. Firstly, in designing the pattern shape, HDS characteristics are taken into account. Secondly, track error signals are analyzed. Thirdly, the discrete pre-pattern intervals are determined according to the track tolerance. Lastly, the feasibility of the new method is analyzed via simulations and experiments.     

Improvement of dynamic characteristics for optical pickup actuator by magnetic circuit

 As disk rotational speed of optical disk drives (ODD) increases, an optical pickup actuator has a high servo bandwidth for its focusing and tracking control to follow dynamic disturbances by high rotational speed in ODD. However, the servo bandwidth is limited by some vibration modes due to the flexibility of the moving part in the actuator. In this paper, the influence of the driving forces generated by VCM on excitation of flexible modes of the moving part in high frequency range is analyzed. Especially, in order to reduce the first flexible mode affecting the servo bandwidth, it is attempted to modify force distribution on coils. The magnetic simulation is performed by using finite element analysis, and compared with experimental results. Finally, it is shown that flexible mode vibration can be suppressed by proper design of magnetic circuit. Received: 20 June 2002 / Accepted: 29 August 2002     

Modeling product variations in hard disk drive micro-actuator suspensions

The increase in aerial storage capacities of future magnetic hard disk drives has fostered the use of dual-stage actuators for high track density data recording. In a hard disk drive with a dual-stage actuator the standard rotary actuation of the voice coil motor is combined with an additional micro or milli actuation to accomplish high-bandwidth and highly accurate track following. In order to guarantee error less data transfer, the track following servo controller needs to perform robustly under different operating conditions, that include changes in flying height and product manufacturing tolerance of the dual-stage actuator. Essential in the controller design is to characterize these uncertain conditions and design a robust track following servo accordingly. In this paper we present an experiment based methodology to characterize the varying servo conditions in the form of an uncertainty model. The uncertainty model can be used for analysis and synthesis of robust servo controllers.     

A fast settling servo controller for high-density disk drives

During seek operation in disk drives, the recording head is moved toward desired track by seek servo controller and then is settled onto the center of the desired track by settling servo controller. If the head speed at the start of settling servo controller is not slow, it may produce overshoot relative to the center of track and thus extend settling time. The degradation in settling performance will be more severe as the track width becomes smaller for high track density. In this paper we discuss the design of settling servo controller which provides fast settling performance without creating overshoot. It is well known that transient response will be much faster if slow poles are canceled out properly. In order to cancel unwanted poles, we apply a sequence of weighted discrete pulse signals to the system in addition to the state feedback control. For exact pole-zero cancellation, we consider the dynamics of power amplifier used for actuator current regulation and the effects of delay in control action. In addition, we present system parameter identification algorithm for the robustness of our controller to system parameter variation. In order to demonstrate the practical use of our controller, we present experimental results obtained by using a commercially available disk drive.This work was supported by the Nuclear Academic Research Program of the Ministry of Science and Technology in Korea.     

磁盘伺服信息非脱机校验方法及实现

随着存储密度的不断提高,磁盘生产过程中伺服刻写及校验的时间消耗愈来愈大,伺服刻写及校验已成为影响磁盘生产质量和效率的瓶颈问题。为此提出了一种新的磁盘伺服信息校验方法-伺服刻写机内的非脱机校验。该校验方法将磁盘驱动器内部的信号处理机制用到伺服刻写机上,从而实现了在伺服刻写机内校验伺服信息。该方法避免了传统的伺服信息校验方法中磁盘盘片的重复装载和拆卸,减少了磁盘伺服刻写及校验在净房内的停留时间,降低了磁盘的生产成本;同时磁盘的质量也因手工操作的减少而得到显著提高。