步进电机定位控制系统的设计

系统基于51单片机控制,以FPGA芯片来实现驱动,步进电机的脉冲分配作为核心电路加以必要的数字模拟辅助电路,形成一个4相8拍步进电机定位控制系统。该系统完成了步进电机的正确脉冲分配并实现了步进电机的方向调节、速度调节及定位控制等功能,由于单片机控制模块的使用使得FPGA驱动模块对步进电机的定位控制更加方便,对步进电机的速度控制精度很高,并且更加准确。     

步进电机脉冲控制信号到频率控制字的转换

为了实现四相步进电机脉冲控制信号控制锁相环电路并且锁相环电路输出信号的频率能够实时反映步进电机的当前角位移量,分析了四相步进电机双四拍控制方式的信号特征,设计了基于FPGA的步进电机控制信号到频率控制字的转换电路,通过实验验证了转换过程的正确性和实时性。改进基于VHDL语言的逻辑功能设计,可用于实现对不同类型步进电机的角位移量化。     

单片机控制步进电机实现光纤光栅外腔半导体激光器调谐

介绍了步进电机在光纤光栅外腔半导体激光器调谐中的应用,利用步进电机角位移与控制脉冲之间的精确同步,控制脉冲宽度与频率,经连杆、齿轮等精密机械传动后,带动千分尺转动,控制光纤光栅拉伸,从而实现利用单片机控制步进电机对外腔半导体激光器波长进行调谐。     

单片机控制步进电机实现光纤光栅外腔半导体激光器调谐

本文介绍了步进电机在光纤光栅外腔半导体激光器调谐中的应用，利用步进电机角位移与控制脉肿之间的精确同步，控制脉冲宽度与频率，经连杆、齿轮等精密机械传动后，带动千分尺转动，控制光纤光光栅拉伸，从而实现利用单片机控制步进电机对外腔半导体激光光栅波长进行调谐。     

一种新型智能调节阀的设计

本文的智能调节阀直接从RS-485总线上获得数字命令,通过单片机控制步进电动机转动。并且通过以电位器式角位移传感器、放大器、ADC构成的位置发送器把阀门的开度信号反馈给单片机,以控制步进电机精确定位,并把阀门开度通过总线传给控制端。     

一种实用的二相步进电机细分控制电路

文章介绍了单片机和步进电机驱动芯片NJM3717构成的两相混合式步进电机的控制系统.重点提出了一种利用电阻特性来实现的细分控制方法,该方法简单有效,能够使用很少的电子元器件来完成步进电机的精确控制.     

基于嵌入式单片机的步进电机控制系统设计的分析

单片机作为步进电机控制系统的中心部分,完成步进电机的硬件电路设计,进而实现步进电机的系统控制,实现智能化控制,进一步提高电机控制的工作效率。本文主要就对嵌入式单片机的步进电机控制系统设计进行分析和研究,以期为界内相关人士提供相关的参考资料,为提高步进电机的工作效率奠定坚实的基础。     

基于89C51单片机的步进电动机控制系统设计

为了实现对步进电动机控制的需求,提出了一种基于89C51单片机控制的步进电动机系统设计方案,并完成步进电动机系统的硬件和软件设计。单片机采用89C51系列,在单片机与步进电机之间选用74LS04与4N29组成的驱动电路,实现对单片机的保护。该系统的软件部分采用进行C编程,能够完成对步进电动机的精确控制。实际应用表明,所设计的控制系统具有操作简便、控制精度高、可靠性好等特点,具有较高的使用价值。     

浅析利用单片机控制步进电机

步进电机作为控制用特种电机,是一种将电脉冲转化为角位移的执行机构。本文重点介绍如何利用STC89C52RC单片机软件编程控制输出脉冲的相序、频率、数量,从而达到控制24BYJ48步进电机的旋转方向、速度以及位置。     

基于PLC驱动控制步进电机的设计与实现

在PLC步进电机控制中,输入到其线圈组中的脉冲数或脉冲频率可控制步进电机的角位移和速度。以三菱的FX2系列为例,讨论了步进电机的PLC控制系统设计与实现。     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.