瞬变电磁场辐照下液晶显示模块的电磁兼容预测

We report on the development of an automated visual inspection system for liquid crystal display (LCD) modules. The system comprises a highly graphical software program, a unique image processing algorithm, a PC interface card for driving different types of LCD modules, and a universal test jig for holding these modules. The system is able to detect faulty or malfunctioning LCD modules with minimum intervention from human operator; allows testing to be carried out for evaluating the display quality such as contrast ratio; is able to create new test databases for new LCD modules; allows permanent storage/backup of test databases for each individual LCD module; and provides a friendly user interface for ease of operation. In addition, the system has the following features: different access levels for different users; an editor for creating software drivers for driving different types of LCD modules; and a graphical help facility.

This paper studies the electromagnetic compatibility (EMC) for the instrumentation & control system, communication devices and electric equipments in commercial nuclear power plants (NPPs). It reviews the EMC research activities and practices for NPPs in United States, France, Russia and China. The paper first familiars the readers with electromagnetic interference (EMI) knowledge and examples that are most related to NPP EMC issues, including EMI source, coupling path and sensitive equipment. It then summarizes the historical research activities, focusing on the development of EMC standards for NPPs in those four countries. It is concluded that the current EMC standard systems are not uniform and lack of specific test procedures and quantification methods. They are insufficient for the nuclear industry to execute. At last, recent popular research topics for NPPs are reviewed including systematic EMC design, EMC design and control measures, EMC prediction and electromagnetic environment monitoring. Similar research work done in the general EMC community or by other industries has been introduced. It indicates that for NPPs EMC design especially at the system level is still immature, electromagnetic simulation can be a good tool to assist the EMC design and that EMC control regulations and environment monitoring become more and more necessary as wireless components and devices are being used.

A calculation method of electromagnetic interference(EMI) margin of spacecraft wireless system is analyzed and researched in this paper, meanwhile the EMI margin is simulated and calculated. The electromagnetic compatibility (EMC) of wireless system is prognosed for a couple of wireless equipment which indicate that there is a risk of EMI among this couple of wireless equipment. According to the simulation results, a series of EMC test including tabletop dispersedly test and comprehensive test has been implemented to verify the prediction method. The test results indicate that there is EMI phenomenon among this couple of wireless equipment which support the accuracy of the prediction method. Combined with simulation and test results, a method for spacecraft wireless system EMC prediction has been proposed. The method will reduce the EMI problem in spacecraft development process and be benefit to subsequent maintenance.

As the trend of consumer electronics and mobile communications devices is obviously developing toward to miniature and high-speed processing, the problem involving with electromagnetic compatibility (EMC) or radio frequency interference (RFI) is becoming more critical for the system integration of high-speed digital and RF mixed signal platforms. This paper is mainly focusing on the characteristics analysis of various electromagnetic shielding materials by utilizing the various shielding effectiveness (SE) measuring methods developed by TDK and ASTM (ASTM D4935). We also adopt the electromagnetic interference (EMI) testing methods developed by IEC for chip level (IEC 61967-3 and IEC 61967-6) to investigate the characteristics and distribution of EMI noise sources. To effectively shield the electric, magnetic, or electromagnetic field originated from noise source, we thus analyze the shielding capability for various materials with different measuring methods. Finally, we will show the EMI reduction and RF performance improvement with implementation of shielding material on module under investigated. With the systematic measurement and analysis described in this paper, we can further identify the related EMI problem and resolve the severe chip or module level EMC problem more effectively.

As the display terminal of military electronic equipment.reinforced liquid crystal display is one of the most direct,main and important key equipment for military personnel to obtain information. In the face of the most complex and severe command and control cabin environment of aircraft,combat vehicles and ships,reinforced liquid crystal display is interfered by and against other equipment all the time. Sudden equipment restart,flash screen,flower screen and other failures,seriously affect the normal operation of equipment,further affect the battlefield judgment of military personnel. This paper summarizes the main functions and working principles of the reinforced LCD,and puts forward the design scheme for the electromagnetic compatibility problems of the reinforced LCD. It is necessary to consider the electromagnetic compatibility at the beginning of the design,reduce the interference and interference risk of the equipment from the source side,and rationally lay out the equipment inside to achieve the ideal electromagnetic compatibility effect..

A wideband measurement technique to characterize radio frequency (RF) interference caused by a liquid crystal display (LCD) baseband noise modulation is proposed. The LCD noise in baseband frequency range modulated with the Tx carrier signal of cellular communication interferes with the Rx signal, resulting in a RF receiver desensitization problem. Since the frequency offset between the Tx and Rx bands is small (several tens of MHz), a high Tx band rejection filter is essential to characterize the relatively small modulation noise with small frequency offset along with the strong Tx carrier signal. A typical solution is to use a duplexer, which only works for the dedicated communication band and, thus, a narrow band. The proposed measurement technique utilizes a 180° hybrid coupler and reflection cancellation to obtain high Tx band rejection without any frequency limited components. In addition, another reflection cancellation method is demonstrated for a large offset frequency case.

Prediction and analysis for inter-system electromagnetic compatibility (EMC) are studied in this paper. To study the EMC status of the systems quantitatively, electromagnetic interference margin (IM) is adopted. The inter-system IM, whether the electromagnetic interference (EMI) occurs among the systems or not can be known. Prediction and analysis of inter-system EMC are done in the information platform, some conclusions and some primary interference suppression steps are made.

Electromagnetic compatibility (EMC) is a critical aspect of electronic and electrical systems, ensuring their ability to function properly within a shared electromagnetic environment without causing or suffering from unacceptable interference. This study employs the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), a multi-criteria decision-making method, to evaluate and rank various EMC parameters. The analysis considers several key EMC factors, including the EMC directive, radiated emissions, conducted emissions, electromagnetic interference (EMI), EMC standards, and electromagnetic susceptibility (EMS). The EMC directive, which serves as a guiding framework for managing electromagnetic disturbances in devices, emerged as the top-ranked criterion, underscoring its pivotal role in regulatory adherence and standardization. Radiated emissions and conducted emissions secured the second and third ranks, respectively, highlighting their substantial impact on EMC performance. Effective management of these emissions is crucial for mitigating potential interference with communication systems, aircraft equipment, and other electronic devices, thereby enhancing the reliability and coexistence of products within the electromagnetic spectrum. Electromagnetic interference (EMI) and EMC standards followed closely, ranking fourth and fifth. EMI shielding and compliance with EMC standards are vital for preventing disruptions caused by electromagnetic radiation and ensuring the smooth operation of electronic circuits and wireless networks. Adherence to these standards promotes interoperability and minimizes the risk of performance degradation. Lastly, electromagnetic susceptibility (EMS) ranked sixth, emphasizing the importance of assessing the sensitivity of electronic devices to electromagnetic energy. By understanding and mitigating EMS, manufacturers can enhance the immunity of their products to external interference, reducing the likelihood of operational issues or physical damage. The TOPSIS method facilitated a comprehensive analysis by considering the ideal and negative ideal solutions, ultimately ranking alternatives based on their proximity to the optimal scenario. The results underscore the multifaceted nature of EMC and the need for a holistic approach that considers various aspects, from regulatory directives to emission control and interference mitigation. By leveraging the TOPSIS method, decision-makers can prioritize and allocate resources effectively, ensuring that EMC challenges are addressed comprehensively and proactively, thereby promoting the harmonious coexistence of electronic systems within the electromagnetic environment.

This paper deals with energy/power quality issues, correlated with Electromagnetic Compatibility (EMC) and electromagnetic interferences (EMI) which appear at urban transportation systems. One presents, briefly, some aspects regarding powers definitions for harmonic and/or unsymmetrical regimes from three-phase circuits, applicable to loads supplied from the a.c. line through low voltage power transformers and uncontrolled three-phase rectifiers. It is analysed the case of a driving system with d.c. motor and chopper, supplied from the d.c. line, which induces a significant non-sinusoidal regime in the a.c. network. The cases in which the load is not compensated, respectively compensated through an active filter are also analyzed through tests on stand. Aspects regarding powers and power flows for both cases are also discussed. Furthermore, the obtained data are compared using the quality standards IEEE 519/1992 and 1459/2000. One discusses the obeying of quality standards and some aspects, which are not approached in the specialty literature, concerning the corresponding EMC and EMI issues. Problems related to the tested driving system connection to the supplying system from the power substation for an urban transportation system are briefly presented. The waveforms of currents through the active filter are depicted. Some conclusions on approaching EMC and EMI at low frequencies, with an extension over 2 kHz and the relation with the IEC 61000-4-30 standard are also presented. It is underlined the necessity of treating energy/power quality issues in correlation with issues regarding EMC and EMI at low frequency for this type of loads.

Electrostatic discharge (ESD) has been known to cause electromagnetic noise against electronic equipment and devices even before the technical concept of electromagnetic compatibility (EMC) was established 68 years ago in the United States and 48 years ago in Japan, while the ESD still continues to be studied as one of the most significant issues that should be solved in EMC areas. This is largely because the underlying nature of ESD has yet to be essentially elucidated from an EMC perspective. On the other hand, as an academic research organization on EMC in Japan, a Technical Committee named ‘EMCJ’ on ‘Environmental Electromagnetic Engineering’ was founded in 1976 in both the Institute of Electrical Engineers of Japan (IEEJ) and the Institute of Electronics and Communication Engineers or the present IEICE (Institute of Electronics, Information and Communication Engineers) to address EMC concerns. Since then, the EMCJ has been jointly conducting EMC research activities under the IEICE as the nominating body and the IEEJ as the associative body, whereas the EMCJ of IEEJ was dissolved in 1999 to form a new Technical Committee on EMC (TC‐EMC) in order to deal with EMC issues appropriate to the IEEJ. In this review, to mark the 25th anniversary of the IEEJ Technical Committee on EMC (TC‐EMC) in 2024, the EMC research efforts and activities that the TC‐EMC has conducted over the past 25 years from January 2000 to March 2024 are surveyed from 1272 technical papers presented at the technical meetings. Furthermore, among the ESD issues identified in these technical papers, the latest case studies utilizing ‘spark resistance laws’ that allow the analysis of the initial behavior of sparks, in which a spark is the essence of ESD and is the key to open the door to elucidate the phenomenon, particularly from an EMC perspective, are reviewed. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

This paper presents chip level techniques to improve electro-magnetic interference (EMI) characteristics of LCD-TV panels. A timing controller (TCON) uses over-driving algorithms to improve the response time of liquid crystals (LC). Since this algorithm needs previous frame data, external memory such as double data rate synchronous DRAM (DDR SDRAM) is widely used as a frame buffer. A TTL interface between the TCON and memory is used for read and write operations, generating EMI noise. For reduction of this EMI, three methods are described. The first approach is to reduce the driving current of data I/O buffers. The second is to adopt spread spectrum clock generation (SSCG), and the third is to apply a proposed algorithm which minimizes data transitions. EMI measurement of a 32" LCD-TV panel shows that these approaches are very effective for reduction of EMI, achieving 20dB reduction at 175MHz.

SUMMARY This paper proposes spread-spectrum clock modulationalgorithms for EMI reduction in digitally-controlled DC-DC converters.In switching regulators using PWM, switching noise and harmonic noiseconcentrated in a narrow spectrum around the switching frequency cancause severe EMI. Spread-spectrum clock modulation can be used to min-imize EMI. In conventional switching regulators using analog control it isvery difficult to realize complex spread-spectrum clocking, however thispaper shows that it is relatively easy to implement spread-spectrum EMI-reduction using digital control. The proposed algorithm was verified usinga power converter simulator (SCAT). key words: PWM control, spread-spectrum clock modulation, EMI,digitally-controlled DC-DC converter 1. Introduction Most portable electronic devices have low-voltage high-current power supplies using high-efficiency switching reg-ulators. However, the considerable switching noise (andEMI) that switching regulators produce is a big demerit.EMI-related regulations are becoming more severe [1]. Reg-ulations prescribe limits on the generation of Electromag-netic Interference (EMI) and also noise-tolerance or Elec-tromagnetic Susceptibility (EMS) requirements; the combi-nation of both EMI and EMS is called EMC (Electromag-netic Compatibility). In many countries it is illegal to sellelectrical and electronic devices that do not comply with lo-cal EMC standards (in many cases devices must be type-approved, or tested and certified as complying). In mostconventional switching regulators, shielding and filteringare used to reduce EMI. While shielding and filtering areeffective ways of reducing noise, penalties associated withthis approach include the cost of transformers and coils andthe size/weight of shielding.We considered, as an alternative to extensive shield-ing and filtering, how to reduce EMI by switching regu-lator control-module design changes. After examining thepossible application of digital control systems with spread-spectrum technology [2]–[5] to analog-controlled switching

Using commercial off the shelf (COTS) computing equipment in military aircraft applications may cause harmful electromagnetic interference (EMI) to other on-board systems, including communication and navigation equipment. An electromagnetic compatibility (EMC) design approach to successfully integrate COTS equipment into an existing military aircraft is described. The following system design and development steps are outlined: (1) requirements definition, (2) preliminary EMC analysis, (3) EMC control measure design, (4) COTS equipment EMI characterization tests, and (5) system level EMC verification.

Since January 1996 all manufacturers have to design their equipment to comply with the protection requirements of the electro-magnetic compatibility (EMC) directive 89/336/EEC of the European Commission. The protection requirements define, that the manufacturer has to minimise the probability of causing or suffering from electromagnetic disturbances. Manufacturers of power drive systems (PDS) normally define a rated input voltage range, rated power range as well as a climatic ambient within which the PDS has to operate. The EMC product standard EN 61800-3 for adjustable speed electrical PDS, on the other hand accepts light load or unloaded test condition during the conducted emission measurement according to the emission standard EN 55011. This paper looks at the EMC behaviour of PDS, especially in combination with an input electromagnetic interference (EMI) filter in function of the supply voltage and its real load condition. Investigation shows direct influence of real ambient and load conditions on EMI filter performance. Therefore in many cases passing the EMC tests in laboratory conditions does not mean fulfilling protection requirements in the field.

PurposeFunctional MRI (fMRI) is a well-established method used to investigate localised brain activation by virtue of the blood oxygen level dependent (BOLD) effect. It often relies on visual presentations using beam projectors, liquid crystal display (LCD) screens, and goggle systems. In this study, we designed an MR compatible, low-cost display unit based on organic light-emitting diodes (OLED) and demonstrated its performance.MethodsA 3.8” dual OLED module and an MIPI-to-HDMI converter board were used. The OLED module was enclosed using a shielded box to prevent noise emission from the display module and the potentially destructive absorption of high power RF from the MRI transmit pulses. The front of the OLED module was covered by a conductive, transparent mesh. Power was supplied from a non-magnetic battery. The shielding of the display was evaluated by directly measuring the electromagnetic emission with the aid of a pickup loop and a low noise amplifier, as well as by examining the signal-to-noise ratio (SNR) of phantom MRI data. The visual angle of the display was calculated and compared to standard solutions. As a proof of concept of the OLED display for fMRI, a healthy volunteer was presented with a visual block paradigm.ResultsThe OLED unit was successfully installed inside a 3 T MRI scanner bore. Operation of the OLED unit did not degrade the SNR of the phantom images. The fMRI data suggest that visual stimulation can be effectively delivered to subjects with the proposed OLED unit without any significant interference between the MRI acquisitions and the display module itself.DiscussionWe have constructed and evaluated the MR compatible, dual OLED display for fMRI studies. The proposed OLED display provides the benefits of high resolution, wide visual angle, and high contrast video images during fMRI exams.