数字电位器DS3906在三基色LED显示屏中的应用

本文介绍了Dallas Sem iconductor最新推出的I2C总线数字电位器DS3906的引脚功能、内部结构、编程方法以及在LED显示屏控制中的应用和使用中的注意事项等。     

LED灯用印制板阻焊颜色一致性研究

LED产品随着像素与分辨率的不断提高,灯珠间距不断减小,PCB的阻焊面将成为显示屏产品的第一直接外观面。阻焊墨色的一致性已成为LED PCB的关键管控项目。本文研究LED板阻焊网印到表面处理的各个环节对墨色的影响,进而研究控制墨色一致性的有效方案。     

Improve uniformity for an indoor visible light communication system

Visible light communication (VLC) is an alternative technology to the radio frequency (RF) for different applications in the indoor and outdoor environments, it could be utilized for illumination and communication simultaneously, and it offers several advantages over contemporary RF technologies such as low power consumption, free license, large bandwidth, and being friendly to the environment. In this paper, an indoor VLC system uniformity improvement in terms of high received power, signal‐to‐noise ratio (SNR), and bit rate, with RMS delay spread reduction, is proposed. It features a novel model that utilizes a 13‐optical attocells configuration on the ceiling. Moreover, proposed model was evaluated at different semi‐angle at half power. The average received power and SNR were improved to 2.85 dBm and 75.5 dB, while achieved received power and SNR levels at the center of the room were 4.92 dBm and 79.5 dB, respectively. A minimum average RMS delay spread of 0.4749 nanoseconds is obtained, while the highest average bit rate calculated is 211 Mb/s. The proposed model provides a better communication quality and meets illumination standards requirements.     

Neuro-controller for broadcast lighting light-emitting diode to express white light with high color rendering index

Technical characteristics analysis related to correlated color temperature (CCT), color rendering, and illuminance is required to use light-emitting diode (LED) as broadcast lighting. In general, to realize a white light source with a high color rendering index (CRI), we selected the appropriate emission intensity of RGBW LED through trial and error. However, the characteristics of the LED light source and environmental conditions make it difficult to perform the procedure several times. The objective of this study was to design a system that could control illuminance, CCT, and ∆uv while having high CRI, as an LED control method for broadcasting lighting. The controller implements using a feed-forward neural network with excellent nonlinear function approximation capability. We measure data directly from the red green blue white (RGBW) LED system for neural network training. We then select data with high CRI from the measured raw data and choose data for neural network learning by removing measurement noise using the quadratic polynomial interpolation method. The performance evaluation confirms that the proposed neural network controller shows excellent results as an RGBW LED controller for broadcast lighting in the Planckian locus and all regions of white light.     

Mini LED背光源在液晶显示面板上的照度均匀性

基于Taguchi实验方法和Tracepro仿真软件,研究了 Mini LED背光模组中LED芯片大小、芯片发光半角、芯片出光面到液晶层的距离等因素,对液晶面板照度均匀性的影响规律并对其进行了相应分析.研究结果表明:芯片出光面到液晶层的距离对照度均匀性影响最大,影响因素的权重占比达到82.88％;发光半角占比14.33％:芯片大小占比为14.33％.根据研究结果,固定发光半角与芯片尺寸,调节出光面与液晶面板层的距离,得到了最优的照度均匀度.     

一种新的基于软件的LED主波长计算方法研究

LED器件一般采用光谱仪对其光谱参数进行测试,利用公式计算出色品坐标,再利用色品坐标计算得到主波长。传统计算主波长的方法是通过先求斜率再查表得到结果,计算过程不够直观。本文提出一种新的可以准确计算LED主波长的方法,并利用软件编程实现,整个计算思路和过程简单直观,易于理解接受。最后对几种单色LED器件进行了实际测试和计算,验证结果证明本方法有较高的准确性,并且可以方便的切换参考光源,得到不同的计算结果。     

基于STC8A8K的智能LED灯条检测仪设计

LED智能背光源技术已成为平板显示产业主导产品技术,已大量应用于电视机、车载导航等各类显示器件中,而LED智能背光源中的核心部分是LED灯条。由于生产工艺、材料的缺陷,灯条在生产时会出现各种短路、开路等故障,为提高生产效率,智能背光源生产厂家极其需要一种能快速检测灯条故障点的设备。目前,智能背光源生产厂家一般都采用进口的检测设备,不少进口检测设备功能较单一,性价比不高。基于STC8A8K的智能LED灯条检测仪,能自动对待检测灯条的工作电压进行判断,输出所需的工作电压点亮灯条,并通过时序驱动,自动检测灯条存在的各种故障。具有检测功能多、检测范围宽、智能化、效率高、性价比高的特点,成品已实际应用于智能背光源生产厂家。     

基于机器视觉的LED TV智能屏检系统的设计与实现

为更好地助力企业转型升级,在自动化生产中引入机器视觉提升工业机器人加工质量与效率,探讨了一种以光学识别为基础的机器视觉方法用于LED TV的屏检技术,实现亮/暗点、横/竖线、BLOB（几何形态）等缺陷的检测;完成了智能屏检系统总体设计,搭建了机器视觉检测的硬件系统,并研制了智能屏检软件系统。对实现智能屏检涉及的光源选择、相机参数确定、屏检算法等关键技术进行了详尽地阐述,且针对不同检测目标和不同尺寸的屏幕进行了实测与分析。实践表明,本装备具有一定的实用性,其在实现生产线上工业机器人的柔性和智能化水平具有重要的应用价值与现实意义,并为机器人应用范围的拓展提供示范。     

The effect of the illuminance of light emitting diode (LED) lamps on long-term memory

In this study, the effect of the illuminance of LED lamps on long term memory is verified in the conditions of 400 lx, 700 lx, 1000 lx according to the standards of study room illuminance between 400 lx, the minimum and 1000 lx, the maximum suggested by KSA 3011. Word fragment task is used to measure the long term memory. As a dependent task, 90 words made up of 7 letters are selected among 2700 words which have low frequency provided by sesame word. According to the experiment result, the rate of long term memory is 60.42% under the condition of 400 lx, which is the most effective, 59.38% under the condition of 700 lx, and 52.68% under 1000 lx. In addition, the p value between 400 lx and 1000 lx is 0.028, which is statistically significant. The significance of this study lies in that the effect of the illuminance of LED lamps on long term memory, rather than the existing issues such as attentiveness or work memory is searched, suggesting the possibility that the lower, rather than lighter the illuminance of LED light is, the more effective long term memory is.     

Influences of substituting Na+ ions in Eu2+, Mn2+ doped Ba9Y2Si6O24 phosphors

Near-ultraviolet (NUV)-excitable phosphors composed of Ba_8.9-(1/2)pNa_pEu_0.1Y₂Si₆O₂₄ (p = 0–0.8) and Ba_8.7-qNa_0.4Eu_0.1Mn_qY₂Si₆O₂₄ (q = 0–0.4) were prepared via a solid-state reaction in a reducing atmosphere. The X-ray diffraction patterns of the obtained phosphors were examined to index the peak positions. After Na⁺ substitution for Ba²⁺ in the Ba_8.9Eu_0.1Y₂Si₆O₂₄ host lattice, the clear shift from green to yellow emission was observed. The Gaussian components of Ba_8.9-(1/2)pNa_pEu_0.1Y₂Si₆O₂₄ (p = 0, 0.4, and 0.8) phosphors were exploited by using the three different Eu²⁺ ion sites in the host lattice. The dependence of the luminescent intensity of the Mn²⁺ co-doped (q = 0–0.4) host lattices on the fixed Na⁺ and Eu²⁺ contents was also investigated. Co-doping Na⁺ with Mn²⁺ and Eu²⁺ emitters in the host structure enabled efficient energy transfer from Eu²⁺ to Mn²⁺. The mechanism underlying this energy transfer was also discussed. The Commission Internationale de I’Eclairage (CIE) coordinates near the yellow and red regions of the obtained phosphors were observed. Each of Ba_8.9Eu_0.1Y₂Si₆O₂₄, Ba_8.7Na_0.4Eu_0.1Y₂Si₆O₂₄, and Ba_8.6Na_0.4Eu_0.1Mn_0.1Y₂Si₆O₂₄ phosphors with a 405 nm LED chip was fabricated. The color rendering index (CRI, R_a) at correlated color temperature (CCT) with the CIE coordinates was exhibited for the LEDs. The thermal quenching and activation energy for the Ba_8.7Na_0.4Eu_0.1Y₂Si₆O₂₄ and Ba_8.6Na_0.4Eu_0.1Mn_0.1Y₂Si₆O₂₄ phosphors were measured.