Local dimming原理及在车载中的应用

Local dimming(局部调光)是一种低成本提升车载显示器对比度和清晰度的技术。在目前OLED技术尚无法突破严苛的汽车环境要求的状况下,局部调光是一种首选的成本和性能兼顾的技术。在满足汽车环境要求的同时,大幅提升了显示器的清晰度,提高了显示内容的辨识度,同时成本的上升也在合理范围内。它能给客户带来更好的体验,使驾驶更为安全。本文对它的工作原理以及如何应用进行了阐述,给读者提供了一种思路和方法来提升车载显示器的对比度。

Local dimming高亮节能恒流控制算法的研究与应用

介绍了local dimming(区域调光)技术对LED背光亮度及整机功率的影响,通过实验数据分析了PWM(脉冲宽度调制)调光控制方式和DC(直流)调光控制方式引起的亮度变化、功率损耗、器件温升等问题,并结合实际案例给出了具体的改善对策。通过实验及大批量的生产验证表明,提出的具有创新性的恒流动态幅值控制算法对LED背光亮度、整机能效、器件温升等都有极大改善,对local dimming恒流控制方案的设计具有重要的借鉴和参考意义。

Local dimming效果与分区数的关系研究

Local dimming(区域背光调控)是改善被动发光的液晶显示器性能的重要技术。采用一套自主开发的仿真算法,在充分验证其准确性后,对液晶显示器的对比度和光晕指数随分区数的变化关系进行了计算仿真与分析,最终形成背光分区数设计指引。分析结果表明:对比度随分区数的增加而增加,RTINGS棋盘格图片最大价值点(导数为1的点)为300分区,要达到足够接近最大对比度,则需要1600分区左右;背光行列分区数为8的倍数时有更好的对比度体现;光晕指数与对比度随分区数变化的趋势相似,RTINGS十字架图片最大价值点(导数为1)为500分区。

一种基于STM32的Local Dimming检测工装

本文针对目前Local Dimming没有专门的检验提出了一种基于STM32的Local Dimming检测工装。此工装兼容多种Local Dimming背光模组控制方案,使用STM32F103RBT6芯片配合简单的外部电路和8421型按键开关实现了Local Dimming背光模组的检测,具有结构简单、性能稳定、成本低廉等特点。

The Implications of Fluorescent Lamp Electronic Ballast Dimming —An Experimental Study

In recent years, fluorescent lamp dimming controls are an integral part of daylight artificial light integrated schemes intended for realization of energy savings. However, dimming, like any lighting option, presents its own particular challenges and potential tradeoffs. In view of this, the present manuscript depicts the preliminary work progress carried out to arrive at a comprehensive idea on dimming implications on key factors: electrical characteristics, photometric distributions of lighting systems and influence on quality as well as quantity of visual environment. The objective is to experimentally establish the acceptable range of dimming control voltage that would satisfy both electrical and photometric performance of luminaire. The vital part of the paper is devoted towards presentation of measurement results. For the experimental analysis, three representative samples of different commercial analog 1-10VDC electronic dimmable ballasts and fluorescent fixtures are compared and evaluated over their control voltage dimming range.

Design of a Novel Multi-Mode LED Dimming and Color Control System

Aiming at the needs of different lighting applications, combined with the characteristics of LED dimming and color control, and using MSP430 digital control technology, a novel LED intelligent dimming and color control system was designed. The system integrated Bluetooth remote, human infrared sensor, voice/gesture control and other control modes, which could achieve LED multi-mode dimming and color intelligent control. System hardware and software were designed to develop a prototype to experimental verification. The designed method proposes new ideas and information for LED control.

Integrated Off-Line Ballast for High Brightness LEDs with Dimming Capability

This paper presents an off-line integrated full ballast to supply a 35W assembly of Power LEDs. The proposed solution integrates an input PFC stage (a flyback converter operating in DCM) and a DC-DC output converter (a buck converter) into a single switch power stage, operating with peak current control. As it will be shown, this control scheme maintains the current through the load constant, regardless of the instantaneous value of the DC link voltage. This issue allows the use of a small capacitor for the DC link, which enhances the overall system reliability. The complete ballast has full dimming capability, and all the analysis and design steps are presented, thus ensuring the fulfilling of the existing regulations. The novelty of the final solution comes from the simplicity and robustness of the control scheme in an integrated compact single-switch power stage. A final prototype of the ballast has been built and tested, and experimental results are shown in the last part of the paper. Finally, conclusions and future developments are shown.

Design and Implementation of High Power Factor LED Driver with Hot Swap, Smart Output Voltage Regulation and Dimming Control

In this paper, a high power factor LED driver with hot swap, smart output voltage regulation and dimming control is proposed. The dimming control is used to change LED brightness. During converter is working, the hot swap function supply users to remove and insert LED module. The smart output voltage can regulate quickly and rightly output voltage in different number of LED series connection. The system consists two stages, one is 50 W flyback converter which is used as power factor corrector, it is input source is 110-220 V, PF （power factor） is about 0,994. The other is Boost DC/DC converter, it can offer 35-60 V of output voltage. Finally, a prototype has been built and tested. The simulation and experimental results are shown to verify the feasibility of the proposed method.

Sunspot Group Detection and Classification by Dual Stream Convolutional Neural Network Method

The automatic detection and analysis of sunspots play a crucial role in understanding solar dynamics and predicting space weather events.This paper proposes a novel method for sunspot group detection and classification called the dual stream Convolutional Neural Network with Attention Mechanism(DSCNN-AM).The network consists of two parallel streams each processing different input data allowing for joint processing of spatial and temporal information while classifying sunspots.It takes in the white light images as well as the corresponding magnetic images that reveal both the optical and magnetic features of sunspots.The extracted features are then fused and processed by fully connected layers to perform detection and classification.The attention mechanism is further integrated to address the“edge dimming”problem which improves the model’s ability to handle sunspots near the edge of the solar disk.The network is trained and tested on the SOLAR-STORM1 data set.The results demonstrate that the DSCNN-AM achieves superior performance compared to existing methods,with a total accuracy exceeding 90%.

儿童青少年使用DIMS镜片联合视觉训练控制近视效果研究

以5~18岁的近视儿童为研究对象,结合接受视觉训练意愿,非随机地分为多区正向光学离焦(DIMS)镜片组和DIMS镜片联合视觉训练组(联合组)观察近视控制的临床效果。对入组儿童的230只眼6个月随访的近视进展数据进行回顾性分析研究,发现所有入组儿童呈现缓慢的近视进展,平均屈光度进展量为(-0.07±0.18)D/半年,平均眼轴增长为(0.04±0.15)mm/半年;2个治疗组儿童的等效球镜度进展程度的分布没有统计学差异(X^(2)=3.200,P>0.05),眼轴进展程度的分布有统计学差异(X^(2)=10.667,P<0.05)。通过6个月的临床随访发现,近视儿童配戴DIMS镜片可以获得良好的屈光度和眼轴进展的控制效果,若同时联合进行视觉训练,对控制眼轴进展有更大帮助。

基于DEMATEL-ISM-MICMAC的低碳城市建设影响因素研究

城市低碳建设不但是国家优先考虑的问题,而且也是推动城市可持续发展与生态文明建设的重要任务。结合DEMATEL-ISM-MICMAC三种方法对低碳城市建设的影响因素进行分析,揭示其内部层级结构以及各因素间的内在联系与作用机理。运用DEMATEL法和ISM法,解析各因素间的层次关联,运用MICMAC法,解析各因素间的驱动依赖关系,为推动我国低碳城市的建设提供政策建议。结果表明:政府财政支持等几个因素是最重要的因素;居民生活水平和城市交通是最直接的因素;经济增长水平等因素是比较重要的因素,在促进低碳城市建设过程中需要更多关注以上因素,从而有效推进低碳城市建设进程。

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.

Radiation dimming and decreasing water clarity fuel underwater darkening in lakes

Long-term decreases in the incident total radiation and water clarity might substantially affect the underwater light environment in aquatic ecosystems.However,the underlying mechanism and relative contributions of radiation dimming and decreasing water clarity to the underwater light environment on a national or global scale remains largely unknown.Here,we present a comprehensive dataset of unprecedented scale in China’s lakes to address the combined effects of radiation dimming and decreasing water clarity on underwater darkening.Long-term total radiation and sunshine duration showed 5.8%and 7.9%decreases,respectively,after 2000 compared to 1961–1970,resulting in net radiation dimming.An in situ Secchi disk depth(SDD)dataset in 170 lakes showed that the mean SDD significantly decreased from 1.80±2.19 m before 1995 to 1.28±1.82 m after 2005.SDD remote sensing estimations for 641 lakes with areas≥10 km^2 showed that SDD markedly decreased from 1.26±0.62 m during 1985–1990 to 1.14±0.66 m during 2005–2010.Radiation dimming and decreasing water clarity jointly caused an approximately 10%decrease in the average available photosynthetically active radiation(PAR)in the euphotic layer.Our results revealed a more important role of decreasing water clarity in underwater darkening than radiation dimming.A meta-analysis of long-term SDD observation data from 61 various waters further elucidated a global extensive underwater darkening.Underwater darkening implies a decrease in water quality for potable water supplies,recession in macrophytes and benthic algae,and decreases in benthic primary production,fishery production,and biodiversity.

Statistical study on the relationship between halo CME and coronal dimming

The data from SOHO/EIT and SOHO/LASCO observations are used to determine the relationship between coronal dimming and full halo CME (coronal mass ejection). The events of full halo CME examined in this study were observed by LASCO co-ronagraphs and taken from the CD AW CME catalog from 1996 to 2008. Dimming events are identified by using difference images taken by EIT at the 195 A passband. We found strong relationship between full halo CMEs and the coronal dimming events, with up to 93.3% of the front-side halo CMEs associated with the EIT 195 A dimming events. Full halo CMEs that show no clear signatures of dimming usually have lower sky plane velocities (【700 km/s) compared to the mean velocity of CMEs associated with dimming.

A Novel Sensing Imaging Equipment Under Extremely Dim Light for Blast Furnace Burden Surface:Starlight High-Temperature Industrial Endoscope

Blast furnace(BF)burden surface contains the most abundant,intuitive and credible smelting information and acquiring high-definition and high-brightness optical images of which is essential to realize precise material charging control,optimize gas flow distribution and improve ironmaking efficiency.It has been challengeable to obtain high-quality optical burden surface images under high-temperature,high-dust,and extremelydim(less than 0.001 Lux)environment.Based on a novel endoscopic sensing detection idea,a reverse telephoto structure starlight imaging system with large field of view and large aperture is designed.Combined with a water-air dual cooling intelligent self-maintenance protection device and the imaging system,a starlight high-temperature industrial endoscope is developed to obtain clear optical burden surface images stably under the harsh environment.Based on an endoscope imaging area model,a material flow trajectory model and a gas-dust coupling distribution model,an optimal installation position and posture configuration method for the endoscope is proposed,which maximizes the effective imaging area and ensures large-area,safe and stable imaging of the device in a confined space.Industrial experiments and applications indicate that the proposed method obtains clear and reliable large-area optical burden surface images and reveals new BF conditions,providing key data support for green iron smelting.

0.01%阿托品滴眼液联合多区正向离焦镜片和高非球面微透镜片控制青少年近视的效果比较

目的:比较多区正向离焦(DIMS)设计镜片和高非球面微透镜(HAL)设计镜片延缓青少年近视进展的效果。方法:本研究为临床随机对照研究,从我院2021-01-01/2023-06-30验配DIMS镜片患者中随机选取(随机数表法,下同)154例为DIMS组,从验配HAL镜片患者中随机选取147例为HAL组。两组患者均每晚一次联合使用0.01%阿托品滴眼液控制近视,所有患者每天配戴眼镜均在12 h以上。记录快速散瞳后等效球镜度(SE)和眼轴长度(AL),两组人员均取右眼数据,比较两组配镜后12 mo的结果。结果:多元线性回归分析发现,基线年龄与SE、AL变化值显著相关(均P<0.01)。DIMS组和HAL组戴镜12 mo SE变化值分别为-0.41±0.18、-0.34±0.13 D(P<0.001);DIMS组和HAL组AL变化值分别为0.31±0.08、0.27±0.06 mm(P<0.001)。将患者分为7-9岁和10-12岁,7-9岁组配戴DIMS镜片12 mo后SE变化值(t=2.250,P=0.025)和AL变化值(t=3.120,P=0.002)均比配戴HAL镜片大,10-12岁组中同样如此(t=5.931、5.033,均P<0.001)。结论:在联合使用0.01%阿托品滴眼液情况下,配戴HAL镜片控制青少年近视屈光度和AL效果比DIMS镜片更好。

A dual-path,current-sensing resistor-free boost LED driver with fast PWM dimming

A boost LED driver featuring a high PWM dimming ratio and optimized efficiency is presented. This LED driver, which has a low dropout voltage and is able to drive 3-7 LEDs in series with constant output current and fast PWM dimming, provides an alternative technique for brightness adjustment. A dual-path control scheme with automatic switching and state maintenance is proposed. Meanwhile, a cascode current mirror structure is applied with the output transistor multiplexed as an LED PWM dimming transistor. Implemented in 0.5 #m 25 V BCD process, the measurement results show that a voltage conversion range of 5 V input to 6-24 V output with constant output current is obtained. With automatically switching dual-path control and an optimized current mirror, the response time during PWM dimming is reduced to as low as 240 ns and the efficiency keeps above 89% over a wide PWM dimming ratio @ 250 mA output current.

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 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.

Dimming control scheme based on hybrid LACO-SCFDM for visible light communications

This paper proposes a hybrid layered asymmetrically clipped optical(HLACO) single-carrier frequency-division multiplexing(SCFDM) scheme for dimmable visible light communication. It designs a signal structure that combines layered asymmetrically clipped optical(LACO)-SCFDM and negative LACO-SCFDM in proportion for improving the inherent weaknesses of orthogonal frequency-division multiplexing(OFDM)-based dimmable schemes and further enhancing the system performance. Compared to the HLACO-OFDM-based dimming scheme, it obtains a lower bit error ratio and enables efficient communication over broader dimming range. Its spectral efficiency realizes 2.875 bit·s^(-1)·Hz^(-1) within the dimming range of 30%–70%, and the attainable average spectral efficiency gains exceed at least 19.21% compared to other traditional dimmable schemes.

基于激光点云批量化自动滤波分类技术研究

通过基于VC++6.0,OPENCV和GDAL/OGR自主开发数据处理软件来实现,直接读取点云数据的统计指标信息,如点密度、点云坐标最小值和最大值、标准差,根据统计的指标信息设置最大最小高程,进行高程异常滤波处理,自动滤除最大最小高程之外的点云,通过均值方差迭代滤波参数设置进行批量均值方差迭代高程异常滤波,进而可以进行批量粗分类,将植被、道路、房屋、水体等非地面点和地面点提取出来,实现激光点云的高效滤波并生成DEM。