基于自适应控制的160WLED16位数字调光系统PWM恒流控制器

以PIC单片机为控制核心,提出了一种基于自适应PID控制器的160WLED16位数字调光系统的PWM恒流控制器的设计方案。用串联在160WLED电路中的电阻对LED电流进行检测得到电压信号,经过放大后,送PIC16F873A单片机的A/D转换器转换为量化值,通过与给定的亮度等级的PWM信号的第一次电流采样为基准电流信号进行比较,改变PWM输出的占空比控制LED的亮度等级。经测试,本系统能够实现160W白光LED在16位各级不同亮度时的恒流控制。     

基于PWM的弱视治疗仪光源设计与实现

目前弱视治疗仪一般都采用白炽灯作为光源,利用电阻限流方式控制光强,存在发光效率低,寿命短,发热量高,体积大,可调光强级别较少,光源亮度不稳定等缺陷。针对这些缺陷,文章采用LED设计光源,利用PWM技术控制灯源光强,选择单片机AT89C52为微控制器,通过C51语言编写控制程序,对单片机输出PWM脉冲占空比进行调节,PWM脉冲直接控制驱动电路输出电流的大小,从而达到控制LED亮度强弱的目的,驱动电路的反馈设计确保了输出电流稳定,使LED光源亮度稳定,不易闪烁,比起传统白炽灯对眼睛的伤害减弱。通过实验,结果表明基于PWM技术驱动的LED光源的亮度稳定,并能提供10级以上的光强。     

一种GaN FET的窄脉冲激光器驱动电源系统设计

针对半导体激光器驱动电路在低纳秒级对激光光脉冲调节困难的问题,研究了一种基于GaN高速半导体器件的半导体激光器的驱动方案,可实现激光光脉冲的宽度、高重复频率的高精度调节;在设计上,利用FPGA门电路现场可编辑、低功耗等特点,基于Xilinx Zynq平台搭建前置时序产生电路,输出时序信号;设计储能电路,通过驱动氮化镓场效应晶体管(GaN FET)作为开关控制储能回路,最终实现激光光脉冲低纳秒级的精密调节;经过实验验证和分析,该驱动电路能稳定输出脉冲宽度3~200 ns可调、重复频率0~1 MHz可调、峰值功率超过70 w、上升沿时间小于5 ns的激光光脉冲信号。     

基于半导体开关皮秒脉冲发生器的研制

本文对光导开光的原理、特性进行了分析。利用高压电源对储能电容充电,激光器在接到触发脉冲指令时,发出脉宽为2ns的光脉冲信号驱动光导开关,储能电容内存储的能量通过光导开关释放到取样电阻上,输出高压脉冲信号。通过对电路基本参数的仿真,得到了光导开关在2ns激光脉冲控制下,输出高压脉冲与控制光脉冲响应良好,上升时间为169ps,脉宽为2ns。     

可重复触发单稳态触发器在检测电路中的应用

＂555＂定时器是一种数模混合中的规模集成电路,它使用灵活、方便,被广泛应用于脉冲的产生、整形、定时和延迟等电路中。由其构成的可重复触发单稳态触发器,能比较方便地得到持续时间更长的输出脉冲宽度。本文介绍了由555定时器构成的可重复触发单稳态触发器的电路构成与工作原理,以人体心律监视电路中失落脉冲检测为例,讨论了其在信号检测电路中的应用,说明在实际生产中,只要将其各个功能加以综合应用,便可得到许多实用电路。     

视觉测量中多光学靶点亮度自适应控制

提出了一种面向大视场高精度视觉测量的多红外目标靶点（红外LED）亮度自适应控制方法。以微控制器PIC16F873A和LED驱动芯片MAX6964作为核心器件,设计了可满足大空间范围内靶点亮度控制需求的多目标靶点控制驱动器。为了使LED在近距测量时的调节精度和远近距离测量时的发光亮度都能满足要求,根据MAX6964输出特点设计了PWM信号输出电路,并采用推挽电路驱动LED。实验证明,目标靶点在CCD相机上成像光斑稳定一致。     

远程控制高时间分辨多通道脉冲发生器设计

基于FPGA为四分幅相机研制了高时间分辨的多通道脉冲发生器;该系统具有4个独立的输出信号,配合高压快门电路实现对分幅相机4个通道曝光时间和延迟的控制;采用FPGA内部计数方法实现各个通道输出脉冲的宽度和延时的精确调节,同时采用光纤通信的方式实现远程控制,并利用高速高压输出驱动接口提高了系统的输出能力;研制的同步脉冲发生器最小时间分辨可达4 ns、输出幅度可达7.5 V、传输距离大于10 km。     

一种高性能脉冲信号处理电路模块

针对电力电子器件驱动脉冲信号性能指标多、要求高、处理难度大的问题,设计并制作一种高性能脉冲信号处理电路模块,采用EDA高速电路技术完成设计,LTspice对电路系统仿真并进行实验测试,测试指标相比国内研究现状有显著提高,实现1 MHz的高速脉冲正向整流,输出电平可控,脉宽调节范围达到20%至60%,上下沿时间控制在25 ns以内,其中下降沿时间低至13 ns,传输延时调节范围20 ns至110 ns,2 MHz脉冲信号各项指标也得到大幅提升,从而有效提高驱动电路与主电路效率。进一步优化器件的选择与布局并采用更精密的制作工艺,有望处理频率高达5 MHz的脉冲信号,使电力电子电路更加集成与高效。     

HB-LED医用手术头灯控制系统的设计与实现

研制了以高亮度LED为光源的医用手术头灯控制系统。该系统由电源路径管理电路、充电管理电路、LED驱动电路和调光电路组成。采用外部电源或者电池双电源供电,可驱动5W的大功率白光LED,同时具备LED亮度连续调节和电池充电管理等功能。LED亮度调节实验和锂电池充电实验表明该控制电路很好地符合了预期的设计要求,LED控制电路具有很强的通用性,体积小、价格低廉,适合于便携式电子产品的设计应用。     

“单片机新手入门实例详解”之二——用ME300B型单片机开发系统学习LED亮度控制原理

早期控制LED亮度的方法一般是采采模拟电路来调节LED的工作电流来实现,这种方式灵活性较差,很难达到智能控制的效果。本文将介绍如何通过一个普通MCS51单片机来产生PWM信号,达到调节LED的亮度的目的。     

基于反激式LED驱动芯片的可控硅调光设计

分析了LED驱动电源设计中的可控硅调光.设计能兼容现行大多数调光器的LED电源是降低LED成本、迅速取代当前节能照明技术的关键.系统地分析了三端双向可控硅的工作原理和LED驱动电路调光的难点,提出了加入damping电阻解决可控硅调光与LED兼容问题的方案.该设计基于AC-DC电源芯片MT7920,并加入了一种相位补偿...     

LED PWM dimming linearity investigation

LED PWM dimming application for large scale LED video displays is analyzed. The need for short light pulse duration is outlined. PWM dimming with short driving pulses is investigated experimentally. The LED response time skew introduces the nonlinearity for PWM dimming. For LED response time skew estimation, a method is suggested that has been successfully applied to measure some of today’s market representative LEDs. PWM dimming nonlinearity can be forecasted using the estimated skew. For a particular driving configuration, it is indicated that LED PWM dimming fails to satisfy the required 14 bit output coding together with the image refresh frequency of 400 Hz. A rough investigation demonstrates that the skew is quite stable. Therefore, the nonlinearity correction for the PWM pulse durations shorter than the skew value should be possible.     

LED调光控制技术在飞机导光板照明中的应用

描述了LED技术在飞机驾驶舱照明控制系统中的应用情况,针对目前民用飞机驾驶舱导光板照明普遍采用的LED电压调光技术和单纯PWM调光技术的不足,提出了改进的LED调光技术方案。新型方案利用组合调光技术和数字调光技术,弥补了传统LED调光技术的不足,并对不同的LED调光控制方案进行了分析,最后提出了LED调光技术的发展方向。     

一款基于通用IC的低成本汽车日行灯HB LED驱动电路的设计

设计了一款基于通用IC LM5022的低成本汽车日行灯HB LED驱动电路,实现了HB LED的恒流驱动和PWM调光,并能满足日行灯的有关驱动要求。详细介绍了调光控制线路的设计,并对调光信号的时序和调光比影响因素等进行了分析,给出了主要实验参数和实验结果,输入电压6～19 V,输出电压40～57 V,PWM调光占空比可调5%～100%,输出LED电流200 mA,有关实验验证了本设计的可行性。     

投影仪的LED光源驱动器的设计

介绍了在采用LED做光源的投影仪中,如何设计LED光源的驱动电路.分析了负压型Buck电路的设计及PWM调光电路、短路保护、过压保护、环路测试等问题.     

大功率智能RGB-LED照明系统的设计

为了满足现代照明市场的需求,设计了一款基于Android Apps控制的RGB-LED智能照明系统.该系统采用了PFC与谐振半桥联合的控制器及其共享的反馈补偿回路,通过WiFi模块与单片机、Android Apps提供可智能控制的PWM,BUCK芯片通过接收不同占空比的脉冲波形来改变输出的电流,从而实现LED灯亮度的调节.又由于不同亮度的三基色灯光可以合成自然界中的任意色光,所以该系统可以实现任意色光的合成.此设计节省了成本,提升了效率、控制精度和调光范围.通过Android Apps的功能测试,完全实现了RGB-LED灯的调光调色和情景模式的智能变换.     

LED 大功率灯精准控制驱动电路设计

This paper designs a precise control drive circuit for LED high power lamp. It takes the STC89C52 single chip microcom- puter chip as the control core, selects the PT4115 as the LED power supply chip, uses the PWM to adjust the brightness mode, and re- alizes the adjustment of brightness. The LED has good characteristic of constant current, little change of light color. The circuit can be controlled by key or infrared light, and provides over-voltage and over-current protection. Through experiments, the circuit has good stability and can be adjusted by software program, which can realize multi-stage and even stepless dimming and achieve accurate dim- ming.     

Power savings and enhancement of gray‐scale capability of LCD TVs with an adaptive dimming technique

Abstract— The luminance of a backlight unit for an LCD TV is adaptively and locally dimmed along with the input video signal in order to reduce the power consumption and also to improve the picture quality. By adopting the zero‐dimensional (0D), 1D, and 2D adaptive dimming techniques, a sample movie having 8.0% post‐gamma average picture levels (APL) could be displayed using 83%, 71%, and 50% of the original backlight power, respectively. For an adoption of the 2D dimming, an LED backlight is preferable. The adaptive‐dimming technique also allows the differential aging characteristics between the LED components and temperature dependence of color and luminance to be overcome. From simulations of a reduction in power consumption, it was found that 40 × 40 pixels is a unit of the local dimming, 30 frames for the sampling period, 24 dimming steps, and an equal‐signal‐step method for determining the dimming factor have been found to be appropriate. The gray‐scale capability of low‐luminance images can also be improved by dimming the backlight luminance and expanding the input signal. By using an LCD TV having an 8‐bit capability, an 11‐bit‐equivalent gray‐scale expression was experimentally proven.     

High‐performance high‐efficiency LED‐backlight driving system for LCD panels

Abstract— A high‐performance high‐efficiency LED‐backlight driving system for liquid‐crystal‐display panels is presented. The proposed LED‐backlight driving system is composed of a high‐efficiency DC‐DC converter capable of operating over a universal AC input voltage (75–265 V) and a high‐performance LED‐backlight sector‐dimming controller. The high efficiency of the system is achieved by using an asymmetrical half‐bridge DC‐DC converter that utilizes a new voltage‐driven synchronous rectifier and an LED‐backlight sector‐dimming controller. This controller regulates current using lossless power semiconductor switches (MOSFETs). The power semiconductor switches of the proposed DC‐DC converter, including the synchronous rectifier switch, operate with zero voltage, achieving high efficiency and low switch voltage stress using the asymmetrical‐PWM and synchronous rectifier techniques. To achieve high performance, the proposed driving system performs the sector dimming and the current regulation using low‐cost microcontrollers and MOSFET switching, resulting in high contrast and brightness. A100‐W laboratory prototype was built and tested. The experimental results verify the feasibility of the proposed system.