一种单级无汞平面光源高压驱动电源的设计与研究

无汞平面光源由于具有无污染、寿命长、响应时间短等优点,因而在液晶背光源和照明领域具有非常广阔的前景。传统的无汞平面光源采用两级或者多级结构,本文给出了一种单级结构的无汞平面光源的高压驱动电源并对其工作原理进行了简要分析。最后设计制作了基于该结构的无汞平面光源电路原型并同传统的多级结构进行了比较,实验证明,采用单级结构可以提高无汞平面光源的发光效率。     

无汞介质阻挡放电型平面光源研究的新进展

无汞介质阻挡放电型平面光源(DBD-FFL)是一种有着优良光电特性的环保光源,既可以为液晶显示提供发光均匀的背光,也可以用作具备成本优势的装饰光源。本文叙述了DBD-FFL在近年来取得的重要研究成果,着重介绍了其在电极结构、介质层材料、放电气体以及驱动技术等核心技术方面的研究进展。     

具有碳纳米管掺杂的场增强型DBD平面光源性能研究

为了降低介质阻挡放电平面光源(DBDL)器件的着火电压以及提高其发光效率,本文提出了一种掺杂型的具有场增强型结构的DBD平面光源,该结构采用碳纳米管(CNT)与荧光粉相混合,在荧光粉表明镀有一层厚度为40 nm的MgO薄膜以提高二次电子发射系数及降低气体放电中产生的离子对CNT的冲击.实验结果表明采用在荧光粉中掺杂CNT以及蒸镀MgO薄膜的DBD平面光源结构可以有效降低器件的着火电压和提高发光效率,同传统无掺杂的结构相比,在气压为50kPa的Ne-15％Xe混合气体时,掺杂比为1 ∶ 5000的DBD平面光源其着火电压降低了10％;在相同输入功率下,其亮度及发光效率提高了约20％.     

浮动电极对PDP单元放电最小维持电压及发光效率的影响

针对一种带有浮动电极的新型PDP单元结构,采用流体模型系统地研究了浮动电极的宽度、间隙以及浮动电极与显示电极平面之间的介质厚度及其相对介电常数对最小维持电压和发光效率的影响,结果发现(1)采用浮动电极后最小维持电压得到了较大幅度的降低;(2)发光效率高,则最小维持电压也高;(3)通过调整浮动电极的间隙,可以实现较高的发光效率,并且最小维持电压增加较少;(4)浮动电极间隙的效率指数最高(发光效率改变量/最小维持电压改变量),而浮动电极与显示电极平面之间介质厚度的效率指数最低.     

无汞平面荧光灯数字调光电路的设计与实现

对无汞平面荧光灯的调光方法进行了分析与研究,实验结果表明,采用脉冲密度调制的数字调光方式不仅可以实现大范围的亮度调节,而且可以降低电路设计的成本和难度。依据上述调光方法,设计并制作了一种基于12寸无汞平面荧光灯的调光电路,试验证明,本文所设计的电路不仅能够降低电路成本,同时能够实现100％～10％宽范围的亮度输出。     

新型介质阻挡放电平面光源高压窄脉冲逆变电源的设计与研究

为了提高介质阻挡放电型平面光源的放电效率,本文设计并给出了一种可用于介质阻挡型平面光源及基于介质阻挡原理的气体放电器件的高压窄脉冲产生电路.该逆变电路包含两个全桥逆变电路部分,通过控制两全桥逆变电路输出脉冲的相位差来实现高压窄脉冲的输出.设计并验证了基于12英寸介质阻挡放电平面光源的电路原型.实验结果表明,该逆变电路可以实现最小脉宽为800 ns,脉冲幅值为4.5 kV的高压窄脉冲;亮度及发光效率随工作频率的升高而升高;当输入功率为36.4W时,亮度可达3200 cd/m2,此时系统发光效率为13.4 lm/W.     

IGBT在无汞平面光源驱动电源中的应用

本文对绝缘栅双极晶体管（IGBT）在无汞平面光源驱动电源中的应用可行性进行了分析。同时对IGBT和金属氧化物半导体场效应晶体管（MOSFET）的性能进行了比较,对IGBT在无汞平面光源中应用的可行性进行了分析。结果表明IGBT在大电流应用场合更具优越性,同时IGBT的温度特性优于MOSFET,采用IGBT可以简化电路结构。基于上述分析,设计了一组采用IGBT的12寸无汞平面光源的驱动电源,实验结果表明采用IGBT可以简化电路结构,降低电路成本。     

LCD用无汞平板背光源

本文介绍了一种新型的无汞平板放电灯。该灯使用无电极的介质阻挡层，在平板内充入Ne-xe（氖-氙）混合气体。在相对较低的气压下。产生等离子体，激发荧光粉发光。该灯结构简单，使用了一种特殊的电极结构，通过调整脉冲电压和波形，即可以获得均匀放电。当优化了气体浓度和驱动条件时。光效可达到100多流明／W；通过与基本元件的简单重复连接，可以制造出大尺寸的平板光源。     

带电子聚焦的氧化锌场发射背光源

液晶显示需要低功耗、均匀度好的光源作为背光源。为了降低功耗,提高显示图像质量,未来的液晶显示需要实现对背光源进行时间与阵列调制。对比现有的液晶显示用背光源,研究制备了氧化锌场发射光源。该光源采用氧化锌纳米针作为场发射阴极,采用平面栅极作为门电极调制结构实现亮度的连续可调,通过带有氧化镁二次电子发射层的金属栅网对电子进行聚焦实现光源的均匀照度。实验结果表明,带电子聚焦的氧化锌场发射光源具有较低的开启场强(1.1V/μm),较小的电压调制区间(小于150V),较高的发光强度(大于1 000cd/m2),且基于电子聚焦结构的设计,实现了光源的均匀稳定照度,可以提高液晶显示的图像质量。带电子聚焦结构的氧化锌场发射光源,既可实现对发光的时间与阵列调制,同时能提高发光的均匀性,将可作为液晶显示的理想背光源。     

具有反射电极的高亮度LED芯片设计

根据光学薄膜原理,针对正装LED芯片设计了5种不同方式的电极结构,得出电流阻挡层SiO2和Al反射镜叠加制备出的反射电极具有较高的反射率,光电特性明显优于常规电极制备出的LED芯片。实验结果表明,该反射电极的反射率比常规电极结构反射率高53.1%,电流阻挡层SiO2可以改进有源区的电流扩展,减小电流堆积效应,而Al作为反射镜可以降低电极对光的吸收,使其发光效率、光强分布、饱和特性曲线和发光角度明显优于常规电极结构。实验采用化学气相沉积(CVD)法配合电子束蒸发制备反射电极,芯片的光功率提高了5.6%,成功制备出高亮度LED芯片。     

侧入式局域动态调光背光聚光特性研究

针对HDR技术在侧入式局域动态调光中的特殊要求,采用结构导光板搭配LED灯条进行聚光,以此提高背光对比度,实现液晶显示器的分区动态调光控制。首先,基于现有导光板出光面亮度分布,确定了导光板出光面微结构为锯齿形,然后利用光线追迹法对结构导光板进行仿真,分析了不同结构的导光板出光面微结构棱高、棱宽比和曲率对聚光性能的影响,结果表明,聚光性与导光板出光面结构直接相关,光学胶折射率为1.49,棱高为20μm,棱宽比为0.47时,聚光性能最佳;根据仿真结果开发了实际背光产品,并对此产品进行了测试,测试结果表明,与传统的导光板相比,使用结构导光板后,背光聚光效果显著,对比度由6.01提升到127.15,满足动态调光聚光性要求。     

Feedback FET logic: a robust, high-speed low-power GaAs logicfamily

Feedback FET logic (FFL) with a special output stage that enables it to drive high on-chip capacitances with low power is discussed. FFL is robust in the face of process and temperature variations. The basic FFL gate is a NOR, but complex gates such as AND-OR-NOT are also practical. FFL is two to four times faster than comparable GaAs direct-coupled FET logic and Si CMOS and Si BiCMOS when driving on-chip capacitances that are typical of large ICs. FFL power at 200 MHz is also lower than CMOS and BiCMOS power by a factor of 2 to 4     

扫描近场圆偏振光学显微镜

提出一种利用镀有金属薄膜的V形无孔光学探针构建的扫描近场光学显微镜,将圆偏振光注入镀有金属薄膜的V形槽内在针尖处形成近场照射光源,并利用探针收集样品表面近场光信号。理论分析表明:探针收集的近场和远场反射光之间存在一定的相位差,该相位差与探针机械结构、探针与样品的距离有关,可通过探针与样品之间的距离加以控制,因此利用偏振性器件可有效抑制远场光强。实验中,探针与样品之间的距离通过范德华力回馈控制,探针操作在接触模式,实验结果显示所测近场与远场光相位相差57,近场光学图像横向分辨率优于12 nm。     

高调光比发光二极管驱动控制器的设计与实现

This paper presents a high dimming ratio light emitting diode （LED） drive controller chip with digital mode dimming （DMD）. The chip is composed of a boost power converter and a dimming control block. A novel constant on time （COT） control strategy is proposed for boost converter to achieve high dimming ratio. In addition, a fast enough load transient response of the converter power stage ensures its high dimming ratio. The COT control circuit operates mainly based on two current-capacitor timers and a finite state machine （FSM）. The LED drive controller chip is designed and fabricated in 1.5μm bipolar CMOS-DMOS （BCD） process with a die area of 1.31 x 1.43 mm^2. Experimental results show that the proposed LED drive system works well. And, as expected, the minimum LED dimming on time of 1.0μs and the corresponding dimming ratio of 1000 ： 1 at 1 kHz dimming frequency are successfully achieved.     

Implementation of a Voltage Multiplier Integrated HID Ballast Circuit With Dimming Control for Automotive Application

High-intensity discharge (HID) lamps are becoming popular substitutes for halogen lamps in automotive headlamps because of the high lumen/watt ratio and the color of the light. In this paper, a ballast (integrated with a voltage multiplier circuit in the secondary winding of the dc converter transformer) with dimming control is presented. The proposed circuit not only eliminates one auxiliary winding but also reduces the voltage across the switch on the primary side and consequently permits the selection of switches with a lower rating. A brief review of the HID circuits is done and compared with the proposed circuit. Experimental results from the prototype are presented. This paper also presents different methods of dimming the automotive HID lamps based on analog and digital control and discusses the relative merits of each of the methods. The dimming control is implemented using both the methods, and experimental results are presented. It is envisaged that the dimming control will provide some flexibility to drivers in the control of HID lamps to suit the driving conditions in the modern cities that are very well lit at night. This paper investigates the merits of each method and discusses the practical issues for implementing such controls.      

Design and implementation of a high dimming ratio LED drive controller

This paper presents a high dimming ratio light emitting diode (LED) drive controller chip with digital mode dimming (DMD). The chip is composed of a boost power converter and a dimming control block. A novel constant on time (COT) control strategy is proposed for boost converter to achieve high dimming ratio. In addition, a fast enough load transient response of the converter power stage ensures its high dimming ratio. The COT control circuit operates mainly based on two current-capacitor timers and a finite state machine (FSM). The LED drive con-troller chip is designed and fabricated in 1.5μm bipolar CMOS-DMOS (BCD) process with a die area of 1.31 × 1.43 mm2. Experimental results show that the proposed LED drive system works well. And, as expected, the minimum LED dimming on time of 1.0μs and the corresponding dimming ratio of 1000 : 1 at 1 kHz dimming frequency are successfully achieved.     

High performance white LED driver with single-wire serial-pulse digital dimming

A high performance white light emitter diode (LED) driver based on boost converter with novel single-wire serial-pulse digital dimming (SWSP) is proposed. The driver uses external serial programmed pulses and internal clock to simplify brightness control. By embedding a 5-bit digital analog converter (DAC) into the driver, wide dimming range is achieved. Moreover, a new dynamic slope compensation circuit is presented and other key circuits of the driver are optimized to get higher efficiency and fast transition response. A practical circuit is implemented with 0.6 um bipolar complementary-metal-oxide-semiconductor double-diffused-metal-oxide-semiconductor (BCD) technology. The simulation results show that the driver can provide both wide output current from 1.3 mA to 42 mA with 32-level digital dimming and higher efficiency up to 83% while it works at 1 MHz switching frequency with the input voltage variation from 2.7 V to 5.5 V.