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。

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。

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。

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.

Dim-YOLOv5n昏暗场景目标检测算法

相比于正常光照场景,照明不良昏暗场景干扰因素较多,图像处理较为复杂,且现有的昏暗目标检测,存在参数量大,识别准确率低等不足。针对昏暗场景下目标检测算法中存在误检与漏检等问题,提出以YOLOv5n算法为基础进行改进的昏暗场景目标检测算法Dim-YOLOv5n。利用嵌入全维动态卷积(omni-dimensional dynamic convolution,ODConv)的轻量化主干ODConv-MobileNetV2替换主干网络,在减少计算量的同时提高检测精度。基于RepGFPN(reparameterized generalized-FPN)方法设计更加轻量高效的LigGFPN(lightweight generalized-FPN)加强特征融合网络,以提高网络特征提取能力,并在此基础上,使用GhostConv(ghost convolution)替换传统卷积,以减少模型的参数量。实验结果表明,改进后算法与原算法相比,检测精度P和召回率R分别提高了5.3个百分点和5个百分点,平均精度均值mAP0.5:0.95和mAP0.5分别提升了8.2个百分点和4.6个百分点,改进的算法在保证模型较小的同时有效提高了检测准确率。

DIMMER检测中采样点数量和判断阀值的研究

旨在研究和探讨DIMMER检测中的采样点数量和判断阀值对检测结果的影响。DIMMER是一种常用于调光的设备,但其使用调制技术可能导致电力质量问题,因此,对DIMMER进行准确检测至关重要。首先介绍了DIMMER检测技术及相关工作,包括采样点数量和判断阀值的设置方法。随后,针对采样点数量,研究了不同采样点数量对检测精度的影响,并提出了优化方法。同时,研究了判断阀值的选择,并探讨了判断阀值与检测准确性间的关系。为验证研究结果的正确性,设计了一系列实验,采集了相关数据并进行了分析。结果表明,采样点数量和判断阀值对DIMMER检测结果具有显著影响。

基于Dim env-YOLO算法的昏暗场景车辆多目标检测

低照度的夜间路况复杂,现有夜间车辆识别相关研究较少,且存在识别方法实时性不高、过多占用硬件资源等不足。针对夜间场景车辆识别干扰因素较多、检测效果不佳的问题,提出一种基于YOLOv4的Dim env-YOLO车辆目标检测算法。利用MobileNetV3网络替换原始YOLOv4中的主干网络,以减少模型参数量。在改进的YOLOv4模型上使用图像暗光增强方法,提高车辆目标在昏暗环境中的可识别性。在此基础上,引入注意力机制加强特征信息选择,同时利用深度可分离卷积降低网络计算量。选取北京部分道路的夜间场景图片自制数据集并进行实验验证,结果表明,在存在高斯噪声、模糊扰动、雨雾夜晚等情况下,Dim env-YOLO算法的测试结果较稳定,对于照度低于30 lx的昏暗条件下的车流,其检测mAP值达到90.49%,对于最常见的轿车类别,mAP值达到96%以上,优于Faster-RCNN、YOLOv3、YOLOv4等网络模型在昏暗光照条件下的检测效果。

Fourier Spectrometer based on Wide-range and Phase-locked Michelson Interferometer with Femtosecond Laser Excitation

A wide-range and phase-locked Michelson interferometer technique is described. This technique combined with femtosecond laser is used to measure the spectrum of the rare-earth ion Nd：YVO4, which presents very high signal to noise ratio of interferometric intensity output and higher spectral resolution than traditional grating spectrophotometer.

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。

Kinematics modeling of a 6-PSS parallel mechanism with wide-range flexure hinges

A novel 6-PSS flexible parallel mechanism was presented,which employed wide-range flexure hinges as passive joints.The proposed mechanism features micron level positioning accuracy over cubic centimeter scale workspace.A three-layer back-propagation(BP) neural network was utilized to the kinematics analysis,in which learning samples containing 1 280 groups of data based on stiffness-matrix method were used to train the BP model.The kinematics performance was accurately calculated by using the constructed BP model with 19 hidden nodes.Compared with the stiffness model,the simulation and numerical results validate that BP model can achieve millisecond level computation time and micron level calculation accuracy.The concept and approach outlined can be extended to a variety of applications.

基于ECT-Dim的前沿技术识别方法——以养老环境辅助生活技术为例

[研究目的]前沿技术是技术创新的制高点,引导着研发的方向,对前沿技术进行及时地识别有助于尽早把握技术发展方向并做出布局。[研究方法]该文构建了基于ECT-Dim的前沿技术识别模型,提出技术新兴性、确定性与探索性测度方式,建立前沿技术筛选机制,以养老环境辅助生活技术为例进行实证研究。[研究结论]研究发现,提出的ECT-Dim模型,在前沿技术识别上更具有优势;养老环境辅助生活前沿技术集中于物理化工材料、电子器件、老年人建筑设计、助行器驱动与控制等领域。

DC-Modulated PFC Buck-Type AC/AC Converter for Light Dimming

Dimmers are very widely applied in theatres,cinemas,dancing-parties, auditoriums and signal systems.They are usually supplied by single-stage AC/AC converters in the past with voltage regulation technique with the disadvantages of high total harmonic distortion,low power factor and poor power transfer efficiency.This paper introduces a novel method-DC-modulation that implements DC/DC conversion technology into AC/AC converters.The DC-modulated single-stage PFC AC/AC converters effectively improved the power factor up to 0.999 and the power transfer efficiency up to 97.8 %.The experimental results verified our design and calculation.This technique will be widely used in light dimming and other industrial applications.

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.

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。

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.

A Novel Method of Auxiliary Power Supply Used in Wide-Range High Voltage Input DC-DC Converter

In high voltage input DC-DC converter, auxiliary winding of isolation transformer is usually used to supply power for control circuit. Due to the wide-range of input voltage, the variable output voltage of auxiliary winding will cause a series of problems, such as variable drive pulse amplitude, increased driver switching devices loss and drive transformer core saturation. This paper analyzes the influence of variable output voltage of auxiliary winding in detail. A novel method is proposed to solve the problem of large variation range of auxiliary winding output voltage, which is adding a buck converter between the auxiliary winding and the control circuit. A dual switch forward convert has been designed with 300 V - 800 V input and 24 V/5 A output. The results show that this method is effective by comparing the different results of using buck converter or not.

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.

基于GLMB滤波的复杂场景下红外弱小目标自适应跟踪算法

针对红外弱小目标在复杂场景下受到漏检和杂波影响,导致跟踪不连续甚至失效的问题,本文提出一种红外弱小目标自适应跟踪算法。在预处理阶段,为了减少不必要的计算,首先定义一种衡量图像复杂度的算法。然后该算法通过计算红外图像多个特征得到场景复杂度来确认场景类型,再根据场景类型选取对应的检测算法提取目标候选位置、灰度以及局部直方图等特征建立对应的量测模型与似然函数。在目标跟踪阶段,为了自适应地匹配广义标签多伯努利(Generalized Labeled Multi-Bernoulli,GLMB)滤波器的滤波参数,在GLMB的基础上提出一种适应视频图像的新生算法进行航迹起始;针对红外图像序列目标检测概率未知的情况,将未知检测概率的基数化概率假设密度(Cardinality Probability Hypothesis Density,CPHD)滤波器集成到GLMB中实时估计目标检测概率以提升跟踪精度。仿真结果表明,所提出算法能有效地排除量测漏检和虚警的干扰,跟踪不同红外复杂场景下的弱小目标。

结合光吸收和大气散射模型的可解释图像去雾网络

在雾霾天气下拍摄的图像存在对比度低和颜色偏移的问题,这会进一步影响后续高级计算机视觉应用的准确性。大气散射模型(Atmospheric Scattering Model,ASM)作为图像去雾中的热门技术之一,越来越受到研究者的关注。然而,现有的基于ASM的方法由于忽略了光陷现象而会引起暗淡效应。为了解决这个问题,构建了一种基于光吸收的可解释图像去雾网络。具体地,首先构建了一种基于光吸收的大气散射模型(Light Absorption-based ASM,LA-ASM),在ASM中引入了由纹理密度和场景深度定义的光吸收系数。此外,构建了一种可解释网络LA-ASMNet,该网络通过学习LA-ASM的雾气成分来辅助图像去雾。基于RESIDE数据集的仿真结果证明了LA-ASMNet在缓解图像去雾暗淡效应方面的有效性。