大屏幕显示系统的研究毕业论文外文文献翻译及原文
毕业设计(论文)外文资料及译文(模板)
大连东软信息学院
毕业设计（论文）外文资料及译文
系所：
专业：
班级：
姓名：
学号：
大连东软信息学院
Dalian Neusoft University of Information
外文资料和译文格式要求
一、装订要求
1、外文资料原文（复印或打印）在前、译文在后、最后为指导教师评定成绩。
2、译文必须采用计算机输入、打印。
3、A4幅面打印，于左侧装订。
二、撰写要求
1、外文文献内容与所选课题相关。
2、本科学生译文汉字字数不少于4000字，高职学生译文汉字字数不少于2000字。
三、格式要求
1、译文字号：中文小四号宋体，英文小四号“Times New Roman”字型，全文统一，首行缩进2个中文字符，1.5倍行距。
2、译文页码：页码用阿拉伯数字连续编页，字体采用“Times New Roman”字体，字号小五，页底居中。
3、译文页眉：眉体使用单线，页眉说明五号宋体，居中“大连东软信息学院本科毕业设计（论文）译文”。
【推荐】大屏幕显示系统LED的发展外文文献翻译
【word版本下载后可任意编辑】The research of the large screen display system'sLed developmentAlong with computer technology's high speed development, LED (Light Emitting Diode) the screen display system takes after the television, the broadcast, the newspaper, the magazine “the fifth big media” marches into the social life fast each aspect. Its collection microelectronic technology, the computer technology, the information processing and management technology in a body, may the information through the writing, the design, the animation and the video frequency four forms demonstrates. With media and so on bank of television monitors, magnetism vane compares, the LED large screen display system has the design to be artistic, the color is sharp; The design, the color change are rich, are fast; The low power loss, the long life, the use cost low, work stably reliable and so on characteristics. It demonstrated the chart article angle of view is big, the apparent distance is far, thus has widely applied in the large-scale square, the commercial advertizing, the sports complexes, the information dissemination, the news issue, the securities trading; It also applies in the industrial control and the industry reassignment system, is advantageous each kind of parameter, the alarm point, the technical process demonstrates clearly perfect, may satisfy the different environment the need. The LED display monitor is one kind of use computer and the complex digital signal processing electron advertisements propaganda screen. Its screen body part by the microprocessor (is mainly monolithic integrated circuit) and the driving circuit control movement, demonstrated the image or the writing obtain by the computer edition software editor. Because the LED display monitor this kind of new generation information graphic display device has the demonstration design to be stable, the power loss is low, life long and so on characteristics, moreover it synthesized each kind of information graphic display device's strong point, and has overcome own insufficiency, because specially a display monitor may demonstrate that the different content, the display mode is rich. Therefore in the public area, it has the intense advertisements propaganda and the information transmission effect, already in the solid demonstrated day by day occupies the dominant position. The LED display monitor's prospects for development are extremely broad, at present toward thehigh luminance, a higher weather fastness, the higher luminous density, the higher illumination uniformity, the reliability, the panchromatic direction is developing. Is composed of the different material's semiconductor can send out the different color the LED crystal spot. At present what applies is broadest is red, the green, yellow LED. But the blue color and the pure green LED development had already achieved the practical stage.LED display monitor's classificationLED display monitor's classified LED display monitor is many kinds of technical synthesis application product, involves photoelectronics, the semiconductor device, the digit electronic circuit, the large scale integrated circuit, the monolithic integrated circuit and the microcomputer and so on each aspect, both has the hardware and to have software. After the LED display monitor is takes the broadcast, the television, the newspaper, the magazine another new communication media. At present the LED display monitor basis uses the place to be different, may divide into the outdoor screen and the indoor screen two kinds, its main difference is photo tube's illumination brightness is different. But acts according to the content which demonstrated different also to be possible to divide into the image screen and the writing screen two kinds, the image screen may the display image as well as multimedia, but writing screen main demonstration writing or simple fixed image. Display image's multimedia outdoor screens are the investment huge (reaches as high as several millions) the large-scale upscale equipment, main application in large-scale public place, image project and some important places. The LED display monitor's application involves to social economy many domains, already spread the transportation, the negotiable securities, the telecommunication, the advertisement, the propaganda and so on each aspect.LED display monitor's trend of developmentAt present the LED display monitor's demonstration to the high luminance, a higher weather fastness, the higher illumination uniformity, a higher reliability, the panchromatic, the multimedia directions develops, system's movement, the operation and the maintenance also to the integration, the network, the intellectualized direction develop. The 21st century's display technology will be the panel display time, the LED display monitor takes one of panel display leadership products to have a bigger development.1. since the high luminance, entire color blue color and the green superelevation brightness LED product has appeared, the cost reduces fast year by year, causes the LED entire colored display monitor product cost to drop, the promoted speed speeds up. At the same time, along with control technology's development and the LED display monitor body stable enhancement, the entire colored LED display monitor's brightness, the color, white balanced achieves the quite ideal effect, definitely may satisfy the outdoors all-weather environmental condition request, moreover the image is clearer, is more exquisite, is sharper.2. after standardization, standardized material, technology mature and market price basic balanced, the LED display monitor's standardization and the standardization will become a tendency which the LED display monitor develops. In recent years industry in development, after several price recedes the adjustment achieves basically balanced, the product quality, the system reliable and so on will become the main competition factor, this had the high request to the LED display monitor's standardization and the standardization. Profession standard and standard system's formation, IS09000 series standard application, causes the LED display monitor profession the development tends the order.3. the product mix diversification along with the informationization society's formation, the information field is even more widespread, the LED display monitor's application prospect is broader. It is estimated that large-scale or the ultra-large LED display monitor will have the change for the mainstream product's aspect, will suit can have in the service industry characteristic and the specialized request small LED display monitor enhances greatly, will be richer face the information service domain's LED display monitor product class and the variety system, the part potential market demand and the application domain will have the breakthrough, like the mass transit, the parking lot, the dining, the hospital and so on comprehension service aspect's information display monitor demand will have a bigger enhancement.Involves the mentality and the principle of workThis system basis classics' circuit design mentality, uses the design method from bottom to top, from the display panel to the actuation board, arrives at the control panel again, carries on the hardware programming, after debugging successfully, receives a telegram the source plate, finally completes the data transmission board and PC machine connects, carries on the PC software programming, completes the demonstration data the production,the extraction, processing, the transmission as well as the demonstration effect real-time control. Each module uses 8 LED lattices to lighten each line by the line scan form red, green, the traffic light, the demonstration writing and the image. The LED lattice's actuation, the decoding, the lock save and so on to be responsible by control panel's digital circuit. Its data reads by the monolithic integrated circuit from the memory, simultaneously the monolithic integrated circuit uses the interrupt mode, carries on the two-way communication through the RS-232 data line and PC machine, from the PC machine gain order or the data, and carries out the movement or the stored datum according to the order. Not only but PC machine carries on many machine serial port correspondences with many monolithic integrated circuits, but must be responsible for the writing input and the typesetting, the production lattice data or the order character, realize the man-machine interaction function.Principle of work this article designs the large-scale LED display monitor becomes by the double primary color lattice LED combination, uses the line-by-line scanning the display mode to demonstrate red, green, the yellow three kind of color random lattice information. The display module uses the line-by-line scanning demonstration the way, its control system take monolithic integrated circuit AT89C52 as a core, uses 74HC154 memories to take the data-carrier storage, actuates 8*8 using latch 74HC595 and 8 group of line driver 2083The LED display module, simultaneously opens the serial port interrupt and superior PC machine carries on many machine correspondences. Through realizes display monitor's many kinds of animation pattern to the monolithic integrated circuit programming to demonstrate: Rolls the screen toward left, rolls the screen toward right, rolls the screen upwardly, rolls the screen downward, on rolls the screen toward left, on rolls the screen toward right, to the Zola curtain, pulls the curtain toward right, pulls the curtain upwardly, pulls the curtain downward, to the right lateral, lightens in turn from left to right, from among to two nearby, lightens in turn. Animation speed adjustable: Divides into 100 grades, lowest is 1 fast, highest is 100 fast. The pattern color is diverse: The background achromatic color, the writing red/green/yellow, the background is red, the writing does not have/the yellow/green, the background green, the writing does not have/yellow/red, the background yellow, the writing does not have/the red/green. Moreover, but also increased several dozens kind of neon light effect animation. The PC machine on display control software may realize functions and so on Chinese character input, typeface choice, words change, and after carrying on the data processing, may in left side simulatethe demonstration whole effect, simultaneously “sees namely obtained” demonstration in underneath preview region. Moreover, this control software also has additional functions and so on text designation, mouse localization, coordinate tracing, time date. PC machine realizes through the RS-232 connection with the demonstration part monolithic integrated circuit's correspondence, interrupts the real-time receive and the transmission data message using the monolithic integrated circuit serial port. Has also given dual attention to monolithic integrated circuit's antigambling ability in the system design, enhanced the systems operation reliability effectively.Shines the second-level tube characteristicThe light emitter diode (light emitting diode, LED), is one kind turns the electrical energy the energy of light the special component, when the electric current achieves the threshold current, the light emitter diode breakover, along with electric current passing, produces the visible light. Light emitter diode's structure mainly ties the chip, the electrode and the optical system constitution by PN. After PN ties performs the direct voltage, P area's hole injection to the N area, N area's electron-injection to the P area, the electron which and the hole meet, pours into after mutually namely produces compound, these minority carriers injection which ties in PN produce the radiation with compound to shine. It is the original radiation illumination, does not need the high injection current to have the granule number reverse distribution, also does not need the optical resonator, the launch right and wrong coherent light. Describes the LED characteristic to have many parameters, between these parameter's relations present misalignment. Therefore, describes these relations with the characteristic curve, has the use value in the project application.LED component's actuationMay know from the LED component's illumination mechanism, when exerts the direct voltage to the LED component, winds through component's forward current to cause its illumination. Therefore the LED actuation is must make its PN knot to be in the forward bias, simultaneously to control its luminous intensity, but must solve the forward current adjustment problem. The concrete drive type has [9] and so on direct-current actuation, constant flow actuation, pulse actuation and scanning actuation, in this system LED component's actuation for scanning actuation.1. direct-current actuation. The direct-current actuation is the simple the actuation。
毕业设计(论文)外文参考文献译文本
武汉工业学院毕业设计（论文）外文参考文献译文本2011届原文出处IBM SYSTEMS JOURNAL, VOL 35, NOS 3&4, 1996毕业设计(论文)题目音乐图像浏览器的设计与实现院（系）计算机与信息工程专业名称计算机科学与技术学生姓名郭谦学生学号070501103指导教师丰洪才译文要求：1、译文内容须与课题（或专业）有联系；2、外文翻译不少于4000汉字。
隐藏数据技术研究数据隐藏，是一种隐秘的数据加密形式，它将数据嵌入到数字媒体之中来达到鉴定，注释和版权保护的目的。
然而，这一应用却受到了一些限制：首先是需要隐藏的数据量，其次是在“主”讯号受到失真的条件影响之下，对于这些需隐藏数据的可靠性的需要。
举例来说，就是有损压缩以及对有损压缩来说数据遇到被拦截，被修改或被第三方移除等操作的免疫程度。
我们同时用传统的和新式技术来探究解决数据隐藏问题的方法并且对这些技术在以下三个方面的应用：版权保护，防止篡改，和增强型数据嵌入做出评估。
我们能非常方便地得到数字媒体并且潜在地改善了其可移植性，信息展现的效率，和信息呈现的准确度。
便捷的数据访问所带来的负面效果包括以下两点：侵犯版权的几率增加或者是有篡改或修改其中内容的可能性增大。
这项工作的目的在于研究知识产权保护条款、内容修改的相关指示和增加注解的方法。
数据隐藏代表了一类用于插入数据的操作，例如版权信息，它利用“主”信号能够感知的最小变化量来进入到各种不同形式的媒体之内，比如图像、声音或本文。
也就是说，嵌入的数据对人类观察者来说应该是既看不见也听不见的。
值得注意的是，数据隐藏虽然与压缩很类似，但与加密解密技术却是截然不同的。
它的目标不是限制或者管理对“主”信号的存取，而是保证被嵌入的数据依然未被破坏而且是可以恢复的。
数据隐藏在数字媒体中的两个重要应用就是提供版权信息的证明，和保证内容完整性。
因此，即使主讯号遭受诸如过滤、重取样，截取或是有损压缩等破坏行为，数据也应该一直在“主”信号中保持被隐藏的特点。
毕设外文文献+翻译1
毕设外文文献+翻译1外文翻译外文原文CHANGING ROLES OF THE CLIENTS、ARCHITECTSAND CONTRACTORS THROUGH BIMAbstract:Purpose –This paper aims to present a general review of the practical implications of building information modelling (BIM) based on literature and case studies. It seeks to address the necessity for applying BIM and re-organising the processes and roles in hospital building projects. This type of project is complex due to complicated functional and technical requirements, decision making involving a large number of stakeholders, and long-term development processes.Design/methodology/approach–Through desk research and referring to the ongoing European research project InPro, the framework for integrated collaboration and the use of BIM are analysed.Findings –One of the main findings is the identification of the main factors for a successful collaboration using BIM, which can be recognised as “POWER”: product information sharing (P),organisational roles synergy (O), work processes coordination (W), environment for teamwork (E), and reference data consolidation (R).Originality/value –This paper contributes to the actual discussion in science and practice on the changing roles and processes that are required to develop and operate sustainable buildings with the support of integrated ICT frameworks and tools. It presents the state-of-the-art of European research projects and some of the first real cases of BIM application inhospital building projects.Keywords:Europe, Hospitals, The Netherlands, Construction works, Response flexibility, Project planningPaper type :General review1. IntroductionHospital building projects, are of key importance, and involve significant investment, and usually take a long-term development period. Hospital building projects are also very complex due to the complicated requirements regarding hygiene, safety, special equipments, and handling of a large amount of data. The building process is very dynamic and comprises iterative phases and intermediate changes. Many actors with shifting agendas, roles and responsibilities are actively involved, such as: the healthcare institutions, national and local governments, project developers, financial institutions, architects, contractors, advisors, facility managers, and equipment manufacturers and suppliers. Such building projects are very much influenced, by the healthcare policy, which changes rapidly in response to the medical, societal and technological developments, and varies greatly between countries (World Health Organization, 2000). In The Netherlands, for example, the way a building project in the healthcare sector is organised is undergoing a major reform due to a fundamental change in the Dutch health policy that was introduced in 2008.The rapidly changing context posts a need for a building with flexibility over its lifecycle. In order to incorporate life-cycle considerations in the building design, construction technique, and facility management strategy, a multidisciplinary collaboration is required. Despite the attempt for establishing integrated collaboration, healthcare building projects still facesserious problems in practice, such as: budget overrun, delay, and sub-optimal quality in terms of flexibility, end-user?s dissatisfaction, and energy inefficiency. It is evident that the lack of communication and coordination between the actors involved in the different phases of a building project is among the most important reasons behind these problems. The communication between different stakeholders becomes critical, as each stakeholder possesses different setof skills. As a result, the processes for extraction, interpretation, and communication of complex design information from drawings and documents are often time-consuming and difficult. Advanced visualisation technologies, like 4D planning have tremendous potential to increase the communication efficiency and interpretation ability of the project team members. However, their use as an effective communication tool is still limited and not fully explored. There are also other barriers in the information transfer and integration, for instance: many existing ICT systems do not support the openness of the data and structure that is prerequisite for an effective collaboration between different building actors or disciplines.Building information modelling (BIM) offers an integrated solution to the previously mentioned problems. Therefore, BIM is increasingly used as an ICT support in complex building projects. An effective multidisciplinary collaboration supported by an optimal use of BIM require changing roles of the clients, architects, and contractors; new contractual relationships; and re-organised collaborative processes. Unfortunately, there are still gaps in the practical knowledge on how to manage the building actors to collaborate effectively in their changing roles, and todevelop and utilise BIM as an optimal ICT support of the collaboration.This paper presents a general review of the practical implications of building information modelling (BIM) based on literature review and case studies. In the next sections, based on literature and recent findings from European research project InPro, the framework for integrated collaboration and the use of BIM are analysed. Subsequently, through the observation of two ongoing pilot projects in The Netherlands, the changing roles of clients, architects, and contractors through BIM application are investigated. In conclusion, the critical success factors as well as the main barriers of a successful integrated collaboration using BIM are identified.2. Changing roles through integrated collaboration and life-cycle design approachesA hospital building project involves various actors, roles, and knowledge domains. In The Netherlands, the changing roles of clients, architects, and contractors in hospital building projects are inevitable due the new healthcare policy. Previously under the Healthcare Institutions Act (WTZi), healthcare institutions were required to obtain both a license and a building permit for new construction projects and major renovations. The permit was issued by the Dutch Ministry of Health. The healthcare institutions were then eligible to receive financial support from the government. Since 2008, new legislation on the management of hospital building projects and real estate has come into force. In this new legislation, a permit for hospital building project under the WTZi is no longer obligatory, nor obtainable (Dutch Ministry of Health, Welfare and Sport, 2008). This change allows more freedom from the state-directed policy, and respectively,allocates more responsibilities to the healthcare organisations to deal with the financing and management of their real estate. The new policy implies that the healthcare institutions are fully responsible to man age and finance their building projects and real estate. The government?s support for the costs of healthcare facilities will no longer be given separately, but will be included in the fee for healthcare services. This means that healthcare institutions must earn back their investment on real estate through their services. This new policy intends to stimulate sustainable innovations in the design, procurement and management of healthcare buildings, which will contribute to effective and efficient primary healthcare services.The new strategy for building projects and real estate management endorses an integrated collaboration approach. In order to assure the sustainability during construction, use, and maintenance, the end-users, facility managers, contractors and specialist contractors need to be involved in the planning and design processes. The implications of the new strategy are reflected in the changing roles of the building actors and in the new procurement method.In the traditional procurement method, the design, and its details, are developed by the architect, and design engineers. Then, the client (the healthcare institution) sends an application to the Ministry of Healthto obtain an approval on the building permit and the financial support from the government. Following this, a contractor is selected through a tender process that emphasises the search for the lowest-price bidder. During the construction period, changes often take place due to constructability problems of the design and new requirements from the client.Because of the high level of technical complexity, and moreover, decision-making complexities, the whole process from initiation until delivery of a hospital building project can take up to ten years time. After the delivery, the healthcare institution is fully in charge of the operation of the facilities. Redesigns and changes also take place in the use phase to cope with new functions and developments in the medical world.The integrated procurement pictures a new contractual relationship between the parties involved in a building project. Instead of a relationship between the client and architect for design, and the client and contractor for construction, in an integrated procurement the client only holds a contractual relationship with the main party that is responsible for both design and construction. The traditional borders between tasks and occupational groups become blurred since architects, consulting firms, contractors, subcontractors, and suppliers all stand on the supply side in the building process while the client on the demand side. Such configuration puts the architect, engineer and contractor in a very different position that influences not only their roles, but also their responsibilities, tasks and communication with the client, the users, the team and other stakeholders.The transition from traditional to integrated procurement method requires a shift of mindset of the parties on both the demand and supply sides. It is essential for the client and contractor to have a fair and open collaboration in which both can optimally use their competencies. The effectiveness of integrated collaboration is also determined by the client?s capacity and strategy to organize innovative tendering procedures.A new challenge emerges in case of positioning an architect in a partnership with the contractor instead of with the client. In case of the architect enters a partnership with the contractor, an important issues is how to ensure the realisation of the architectural values as well as innovative engineering through an efficient construction process. In another case, the architect can stand at the client?s side in a strategic advisory role instead of being the designer. In this case, the architect?s responsibility is translating client?s requirements and wishes into the architectural values to be included in the design specification, and evaluating the contractor?s proposal against this. In any of this new role, the architect holds the responsibilities as stakeholder interest facilitator, custodian of customer value and custodian of design models.The transition from traditional to integrated procurement method also brings consequences in the payment schemes. In the traditional building process, the honorarium for the architect is usually based on a percentage of the project costs; this may simply mean that the more expensive the building is, the higher the honorarium will be. The engineer receives the honorarium based on the complexity of the design and the intensity of the assignment. A highly complex building, which takes a number of redesigns, is usually favourable for the engineers in terms of honorarium. A traditional contractor usually receives the commission based on the tender to construct the building at the lowest price by meeting the minimum specifications given by the client. Extra work due to modifications is charged separately to the client. After the delivery, the contractor is no longer responsible for the long-term use of the building. In the traditional procurement method, all risks are placed with theclient.In integrated procurement method, the payment is based on the achieved building performance; thus, the payment is non-adversarial. Since the architect, engineer and contractor have a wider responsibility on the quality of the design and the building, the payment is linked to a measurement system of the functional and technical performance of the building over a certain period of time. The honorarium becomes an incentive to achieve the optimal quality. If the building actors succeed to deliver a higher added-value thatexceed the minimum client?s requirements, they will receive a bonus in accordance to the client?s extra gain. The level of transparency is also improved. Open book accounting is an excellent instrument provided that the stakeholders agree on the information to be shared and to its level of detail (InPro, 2009).Next to the adoption of integrated procurement method, the new real estate strategy for hospital building projects addresses an innovative product development and life-cycle design approaches. A sustainable business case for the investment and exploitation of hospital buildings relies on dynamic life-cycle management that includes considerations and analysis of the market development over time next to the building life-cycle costs (investment/initial cost, operational cost, and logistic cost). Compared to the conventional life-cycle costing method, the dynamic life-cycle management encompasses a shift from focusing only on minimizing the costs to focusing on maximizing the total benefit that can be gained. One of the determining factors for a successful implementation of dynamic life-cycle management is the sustainable design of the building and building components, which means that the design carriessufficient flexibility to accommodate possible changes in the long term (Prins, 1992).Designing based on the principles of life-cycle management affects the role of the architect, as he needs to be well informed about the usage scenarios and related financial arrangements, the changing social and physical environments, and new technologies. Design needs to integrate people activities and business strategies over time. In this context, the architect is required to align the design strategies with the organisational, local and global policies on finance, business operations, health and safety, environment, etc.The combination of process and product innovation, and the changing roles of the building actors can be accommodated by integrated project delivery or IPD (AIA California Council, 2007). IPD is an approach that integrates people, systems, business structures and practices into a process that collaboratively harnesses the talents and insights of all participants to reduce waste and optimize efficiency through all phases of design, fabrication and construction. IPD principles can be applied to a variety of contractual arrangements. IPD teams will usually include members well beyond the basic triad of client, architect, and contractor. At a minimum, though, an Integrated Project should include a tight collaboration between the client, the architect, and the main contractor ultimately responsible for construction of the project, from the early design until the project handover. The key to a successful IPD is assembling a team that is committed to collaborative processes and is capable of working together effectively. IPD is built on collaboration. As a result, it can only be successful if the participants share and apply common values and goals.3. Changing roles through BIM applicationBuilding information model (BIM) comprises ICT frameworks and tools that can support the integrated collaboration based on life-cycle design approach. BIM is a digital representation of physical and functional characteristics of a facility. As such it serves as a shared knowledge resource for information about a facility forming a reliable basis for decisions during its lifecycle from inception onward (National Institute of Building Sciences NIBS, 2007). BIM facilitates time and place independent collaborative working. A basic premise of BIM is collaboration by different stakeholders at different phases of the life cycle of a facility to insert, extract, update or modify information in the BIM to support and reflect the roles of that stakeholder. BIM in its ultimate form, as a shared digital representation founded on open standards for interoperability, can become a virtual information model to be handed from the design team to the contractor and subcontractors and then to the client.BIM is not the same as the earlier known computer aided design (CAD). BIM goes further than an application to generate digital (2D or 3D) drawings. BIM is an integrated model in which all process and product information is combined, stored, elaborated, and interactively distributed to all relevant building actors. As a central model for all involved actors throughout the project lifecycle, BIM develops andevolves as the project progresses. Using BIM, the proposed design and engineering solutions can be measured against the client?s requirements and expected building performance. The functionalities of BIM to support the design process extend to multidimensional (nD), including: three-dimensional visualisation and detailing, clash detection, material schedule, planning, costestimate, production and logistic information, and as-built documents. During the construction process, BIM can support the communication between the building site, the factory and the design office– which is crucial for an effective and efficient prefabrication and assembly processes as well as to prevent or solve problems related to unforeseen errors or modifications. When the building is in use, BIM can be used in combination with the intelligent building systems to provide and maintain up-to-date information of the building performance, including the life-cycle cost.To unleash the full potential of more efficient information exchange in the AEC/FM industry in collaborative working using BIM, both high quality open international standards and high quality implementations of these standards must be in place. The IFC open standard is generally agreed to be of high quality and is widely implemented in software. Unfortunately, the certification process allows poor quality implementations to be certified and essentially renders the certified software useless for any practical usage with IFC. IFC compliant BIM is actually used less than manual drafting for architects and contractors, and show about the same usage for engineers. A recent survey shows that CAD (as a closed-system) is still the major form of technique used in design work (over 60 per cent) while BIM is used in around 20 percent of projects for architects and in around 10 per cent of projects for engineers and contractors.The application of BIM to support an optimal cross-disciplinary and cross-phase collaboration opens a new dimension in the roles and relationships between the building actors. Several most relevant issues are: the new role of a model manager; the agreement on the access right and IntellectualProperty Right (IPR); the liability and payment arrangement according to the type of contract and in relation to the integrated procurement; and the use of open international standards.Collaborative working using BIM demands a new expert role of a model manager who possesses ICT as well as construction process know-how (InPro, 2009). The model manager deals with the system as well as with the actors. He provides and maintains technological solutions required for BIM functionalities, manages the information flow, and improves the ICT skills of the stakeholders. The model manager does not take decisions on design and engineering solutions, nor the organisational processes, but his roles in the chain of decision making are focused on:the development of BIM, the definition of the structure and detail level of the model, and the deployment of relevant BIM tools, such as for models checking, merging, and clash detections;the contribution to collaboration methods, especially decision making and communication protocols, task planning, and risk management;and the management of information, in terms of data flow and storage, identification of communication errors, and decision or process (re-)tracking.Regarding the legal and organisational issues, one of the actual questions is: “In what way does the intellectual property right (IPR) in collaborative working using BIM differ from the IPR in a traditional teamwork?”. In terms of combine d work, the IPR of each element is at tached to its creator. Although it seems to be a fully integrated design, BIM actually resulted from a combination of works/elements; for instance: the outline of the building design, is created by the architect, the design for theelectrical system, is created by the electrical contractor, etc. Thus, in case of BIM as a combined work, the IPR is similar to traditional teamwork. Working with BIM with authorship registration functionalities may actually make it easier to keep track of the IPR.How does collaborative working, using BIM, effect the contractual relationship? On the one hand,collaborative working using BIM does not necessarily change the liability position in the contract nor does it obligate an alliance contract. The General Principles of BIM A ddendum confirms: …This does not effectuate or require a restructuring of contractual relationships or shifting of risks between or among the Project Participants other than as specifically required per the Protocol Addendum and its Attachments? (ConsensusDOCS, 2008). On the other hand, changes in terms of payment schemes can be anticipated. Collaborative processes using BIM will lead to the shifting of activities from to the early design phase. Much, if not all, activities in the detailed engineering and specification phase will be done in the earlier phases. It means that significant payment for the engineering phase, which may count up to 40 per cent of the design cost, can no longer be expected. As engineering work is done concurrently with the design, a new proportion of the payment in the early design phase is necessary.4. Review of ongoing hospital building projects using BIMIn The Netherlands, the changing roles in hospital building projects are part of the strategy, which aims at achieving a sustainable real estate in response to the changing healthcare policy. Referring to literature and previous research, the main factors that influence the success of the changing roles can be concluded as: the implementation of an integrated procurementmethod and a life-cycle design approach for a sustainable collaborative process; the agreement on the BIM structure and the intellectual rights; and the integration of the role of a model manager. The preceding sections have discussed the conceptual thinking on how to deal with these factors effectively. This current section observes two actual projects and compares the actual practice with the conceptual view respectively.The main issues, which are observed in the case studies, are: the selected procurement method and the roles of the involved parties within this method;the implementation of the life-cycle design approach;the type, structure, and functionalities of BIM used in the project;the openness in data sharing and transfer of the model, and the intended use of BIM in the future; and the roles and tasks of the model manager.The pilot experience of hospital building projects using BIM in the Netherlands can be observed at University Medical Centre St Radboud (further referred as UMC) and Maxima Medical Centre (further referred as MMC). At UMC, the new building project for the Faculty of Dentistry in the city of Nijmegen has been dedicated as a BIM pilot project. At MMC, BIM is used in designing new buildings for Medical Simulation and Mother-and-Child Centre in the city of Veldhoven.The first case is a project at the University Medical Centre (UMC) St Radboud. UMC is more than just a hospital. UMC combines medical services, education and research. More than 8500 staff and 3000 students work at UMC. As a part of the innovative real estate strategy, UMC has considered to use BIM for its building projects. The new development of the Faculty ofDentistry and the surrounding buildings on the Kapittelweg in Nijmegen has been chosen as a pilot project to gather practical knowledge and experience on collaborative processes with BIM support.The main ambition to be achieved through the use of BIM in the building projects at UMC can be summarised as follows: using 3D visualisation to enhance the coordination and communication among the building actors, and the user participation in design;integrating the architectural design with structural analysis, energy analysis, cost estimation, and planning;interactively evaluating the design solutions against the programme of requirements and specifications;reducing redesign/remake costs through clash detection during the design process; andoptimising the management of the facility through the registration of medical installations andequipments, fixed and flexible furniture, product and output specifications, and operational data.The second case is a project at the Maxima Medical Centre (MMC). MMC is a large hospital resulted from a merger between the Diaconessenhuis in Eindhoven and St Joseph Hospital in Veldhoven. Annually the 3,400 staff of MMC provides medical services to more than 450,000 visitors and patients. A large-scaled extension project of the hospital in Veldhoven is a part of its real estate strategy. A medical simulation centre and a women-and-children medical centre are among the most important new facilities within this extension project. The design has been developed using 3D modelling with several functionalities of BIM.The findings from both cases and the analysis are as follows.Both UMC and MMC opted for a traditional procurement method in which the client directly contracted an architect, a structural engineer, and a mechanical, electrical and plumbing (MEP) consultant in the design team. Once the design and detailed specifications are finished, a tender procedure will follow to select a contractor. Despite the choice for this traditional method, many attempts have been made for a closer and more effective multidisciplinary collaboration. UMC dedicated a relatively long preparation phase with the architect, structural engineer and MEP consultant before the design commenced. This preparation phase was aimed at creating a common vision on the optimal way for collaboration using BIM as an ICT support. Some results of this preparation phase are: a document that defines the common ambition for the project and the collaborative working process and a semi-formal agreement that states the commitment of the building actors for collaboration. Other than UMC, MMC selected an architecture firm with an in-house engineering department. Thus, the collaboration between the architect and structural engineer can take place within the same firm using the same software application.Regarding the life-cycle design approach, the main attention is given on life-cycle costs, maintenance needs, and facility management. Using BIM, both hospitals intend to get a much better insight in these aspects over the life-cycle period. The life-cycle sustainability criteria are included in the assignments for the design teams. Multidisciplinary designers and engineers are asked to collaborate more closely and to interact with the end-users to address life-cycle requirements. However, ensuring the building actors to engage in an integrated collaboration to generate sustainable design solutions that meet the life-cycle。
【推荐】大屏幕显示系统LED的发展外文文献翻译
大屏幕显示系统LED的发展外文文献翻译The research of the large screen display system'sLed developmentAlong with computer technology's high speed development, LED (Light Emitting Diode) the screen display system takes after the television, the broadcast, the newspaper, the magazine “the fifth big media” marches into the social life fast each aspect. Its collection microelectronic technology, the computer technology, the information processing and management technology in a body, may the information through the writing, the design, the animation and the video frequency four forms demonstrates. With media and so on bank of television monitors, magnetism vane compares, the LED large screen display system has the design to be artistic, the color is sharp; The design, the color change are rich, are fast; The low power loss, the long life, the use cost low, work stably reliable and so on characteristics. It demonstrated the chart article angle of view is big, the apparent distance is far, thus has widely applied in the large-scale square, the commercial advertizing, the sports complexes, the information dissemination, the news issue, the securities trading; It also applies in the industrial control and the industry reassignment system, is advantageous each kind of parameter, the alarm point, the technical process demonstrates clearly perfect, may satisfy the different environment the need. The LED display monitor is one kind of use computer and the complex digital signal processing electron advertisements propaganda screen. Its screen body part by the microprocessor (is mainly monolithic integrated circuit) and the driving circuit control movement, demonstrated the image or the writing obtain by the computer edition software editor. Because the LED display monitor this kind of new generation information graphic display device has the demonstration design to be stable, the power loss is low, life long and so on characteristics, moreover it synthesized each kind of information graphic display device's strong point, and has overcome own insufficiency, because specially a display monitor may demonstrate that the different content, the display mode is rich. Therefore in the public area, it has the intense advertisements propaganda and the information transmission effect, already in the solid demonstrated day by day occupies the dominant position. The LED display monitor's prospects for development are extremely broad, at present toward the high luminance, a higher weather fastness, the higher luminous density, the higher illumination uniformity, the reliability, the panchromatic direction is developing. Is composed of the different material's semiconductor can send out the different color theLED crystal spot. At present what applies is broadest is red, the green, yellow LED. But the blue color and the pure green LED development had already achieved the practical stage.LED display monitor's classificationLED display monitor's classified LED display monitor is many kinds of technical synthesis application product, involves photoelectronics, the semiconductor device, the digit electronic circuit, the large scale integrated circuit, the monolithic integrated circuit and the microcomputer and so on each aspect, both has the hardware and to have software. After the LED display monitor is takes the broadcast, the television, the newspaper, the magazine another new communication media. At present the LED display monitor basis uses the place to be different, may divide into the outdoor screen and the indoor screen two kinds, its main difference is photo tube's illumination brightness is different. But acts according to the content which demonstrated different also to be possible to divide into the image screen and the writing screen two kinds, the image screen may the display image as well as multimedia, but writing screen main demonstration writing or simple fixed image. Display image's multimedia outdoor screens are the investment huge (reaches as high as several millions) the large-scale upscale equipment, main application in large-scale public place, image project and some important places. The LED display monitor's application involves to social economy many domains, already spread the transportation, the negotiable securities, the telecommunication, the advertisement, the propaganda and so on each aspect.LED display monitor's trend of developmentAt present the LED display monitor's demonstration to the high luminance, a higher weather fastness, the higher illumination uniformity, a higher reliability, the panchromatic, the multimedia directions develops, system's movement, the operation and the maintenance also to the integration, the network, the intellectualized direction develop. The 21st century's display technology will be the panel display time, the LED display monitor takes one of panel display leadership products to have a bigger development.1. since the high luminance, entire color blue color and the green superelevation brightness LED product has appeared, the cost reduces fast year by year, causes the LED entire colored display monitor product cost to drop, the promoted speed speeds up. At thesame time, along with control technology's development and the LED display monitor body stable enhancement, the entire colored LED display monitor's brightness, the color, white balanced achieves the quite ideal effect, definitely may satisfy the outdoors all-weather environmental condition request, moreover the image is clearer, is more exquisite, is sharper.2. after standardization, standardized material, technology mature and market price basic balanced, the LED display monitor's standardization and the standardization will become a tendency which the LED display monitor develops. In recent years industry in development, after several price recedes the adjustment achieves basically balanced, the product quality, the system reliable and so on will become the main competition factor, this had the high request to the LED display monitor's standardization and the standardization. Profession standard and standard system's formation, IS09000 series standard application, causes the LED display monitor profession the development tends the order.3. the product mix diversification along with the informationization society's formation, the information field is even more widespread, the LED display monitor's application prospect is broader. It is estimated that large-scale or the ultra-large LED display monitor will have the change for the mainstream product's aspect, will suit can have in the service industry characteristic and the specialized request small LED display monitor enhances greatly, will be richer face the information service domain's LED display monitor product class and the variety system, the part potential market demand and the application domain will have the breakthrough, like the mass transit, the parking lot, the dining, the hospital and so on comprehension service aspect's information display monitor demand will have a bigger enhancement.Involves the mentality and the principle of workThis system basis classics' circuit design mentality, uses the design method from bottom to top, from the display panel to the actuation board, arrives at the control panel again, carries on the hardware programming, after debugging successfully, receives a telegram the source plate, finally completes the data transmission board and PC machine connects, carries on the PC software programming, completes the demonstration data the production, the extraction, processing, the transmission as well as the demonstration effect real-time control. Each module uses 8 LED lattices to lighten each line by the line scan form red, green, the traffic light, the demonstration writing and the image. The LED lattice'sactuation, the decoding, the lock save and so on to be responsible by control panel's digital circuit. Its data reads by the monolithic integrated circuit from the memory, simultaneously the monolithic integrated circuit uses the interrupt mode, carries on the two-way communication through the RS-232 data line and PC machine, from the PC machine gain order or the data, and carries out the movement or the stored datum according to the order. Not only but PC machine carries on many machine serial port correspondences with many monolithic integrated circuits, but must be responsible for the writing input and the typesetting, the production lattice data or the order character, realize the man-machine interaction function.Principle of work this article designs the large-scale LED display monitor becomes by the double primary color lattice LED combination, uses the line-by-line scanning the display mode to demonstrate red, green, the yellow three kind of color random lattice information. The display module uses the line-by-line scanning demonstration the way, its control system take monolithic integrated circuit AT89C52 as a core, uses 74HC154 memories to take the data-carrier storage, actuates 8*8 using latch 74HC595 and 8 group of line driver 2083The LED display module, simultaneously opens the serial port interrupt and superior PC machine carries on many machine correspondences. Through realizes display monitor's many kinds of animation pattern to the monolithic integrated circuit programming to demonstrate: Rolls the screen toward left, rolls the screen toward right, rolls the screen upwardly, rolls the screen downward, on rolls the screen toward left, on rolls the screen toward right, to the Zola curtain, pulls the curtain toward right, pulls the curtain upwardly, pulls the curtain downward, to the right lateral, lightens in turn from left to right, from among to two nearby, lightens in turn. Animation speed adjustable: Divides into 100 grades, lowest is 1 fast, highest is 100 fast. The pattern color is diverse: The background achromatic color, the writing red/green/yellow, the background is red, the writing does not have/the yellow/green, the background green, the writing does not have/yellow/red, the background yellow, the writing does not have/the red/green. Moreover, but also increased several dozens kind of neon light effect animation. The PC machine on display control software may realize functions and so on Chinese character input, typeface choice, words change, and after carrying on the data processing, may in left side simulate the demonstration whole effect, simultaneously “sees namely obtained” demonstration in underneath preview region. Moreover, this control software also has additional functions and so on text designation, mouse localization, coordinate tracing, time date. PC machine。
关于LED的外文文献和中文译文
多个LED发光装置的新型采集系统作为光源的一种，发光二极管（LED）有很多优点。
LED集成度更高，颜色种类多，使用寿命更长，而且工作电压较低。
但是，它仍有一个非常大的缺陷：一只LED的光照强度还是比较低。
这个缺点导致显示屏上的光通量不会很高。
但是无论如何，LED还是以其出色的性能在低电压装置中普遍应用。
因此，利用此系统采集多个LED的光，集成为更高强度的照明装置。
本设计提出三种采集系统，来实现增强光强的功能。
效率最好的一种采集系统可以达到96%。
同时，还分析了本系统的制造误差以及预算。
1 简介利用传统的光源来设计一个便携式探照灯，尺寸和能耗会很大。
而利用LED 来设计将会避免这些问题。
LED有很多优点：节能、体积较小、使用寿命长（约100,103小时）等，尤其是LED的光很适合环境工作。
Carel Zeiss和Philips打算用LED光源设计两种便携式探照灯。
尽管LED有诸多优点，可以让他们设计出的探照灯更加便携和小巧，但是由于光学元件的转换效率问题，导致系统有很多困难。
解决这个困难将是本文研究的重点。
通常，用一种合成非线性集中器（CPC）来减小分散度。
但是，这种传统的CPC采集效率仅为72%，必须要改善采集效率来提高光的利用率。
本文中将解决分散度和采集效率两个问题。
为实现这个目标，设计了三种不同的采集系统，以提高效率，下面逐一介绍。
2 仿真部分利用光学仿真软件和标签查找模块（BRO），来设计并分析采集系统的性能。
LED光源部分来自Osram-Opical半导体。
远程LED光源是一种Lambertian模式，LED的规格见表1。
在采集系统的底部有四个LED。
系统各个LED之间的位置关系如图1。
通光部分为2.1×2.1mm2，孔径3.26mm。
LED阵列对称的分布于系统的底部。
采集系统的第一个光学元件为均质器。
这个均质器的受光角度是12.5°。
因此，这个系统就是要把LED的受光角度的范围控制在±60°到±12.5°之间。
LED显示屏控制程序开发外文文献3
A Robotic Spectrometer System for LED Display MeasurementsGlennMercierJonathanRoss UNLV UNLVmercierg@ tothenorth@ Dr.PaoloGinobbiDr.RamaVenkat UNLV UNLV ginobbi@ venkat@AbstractModern display systems use expensive Light Emitting Diode (LED)s, which eventually may fail or not perform as expected due to harsh weather and other environmental factors. A robotic spectrometer system is developed for measuring the output characteristics of each LED in every pixel and store them in a lookup table. This allows the system to adjust the output of each LED based on the results of the lookup table and helps to maintain the picture quality of the display. This system also allows the use of off-the-shelf LEDs, whose operating characteristics are measured by the robotic spectrometer system in order to identify the optimal operating point. This system facilitates a viable method to improve existing displays, obtain better picture quality, and build displays with off-the-shelf components.1. IntroductionAutomation is a large part of the technological world today. Automation has not only relieved humans of mundane and repetitive tasks on the factory assembly line, it has also insured quality and precision of the assembled products.The quality of LED displays deteriorate over time due to natural degradation of the LEDs and various environmental factors such as heat, humidity, dust, rain, and snow. Since high picture quality LED displays are very expensive, it is not economical to change the entire display. Also, degradation of the quality of the picture may be subtle and may occur over a long period of time, which is hard for human beings to identify. Additionally, LED displays are expensive because the LEDs themselves are very expensive due to negligible quality variation of the LEDs in terms of the luminosity characteristics. If one were to use LEDs from a lot with varying quality, the cost of the displays can be brought down considerably.The aim of this project is to develop a robotic system with a spectroscopic head so that measurements of luminosity and operating characteristics of each individual LED can be measured accurately and stored in memory. If such an automated system can be incorporated as part of a display and hidden at the back of the display when not in use, it will facilitate periodic measurements (e.g. six months) in the field. The measurement, in turn, will help in identifying the need to change the operating characteristics and rectify the problem when identified. Such a system will also help build low-cost displays with reasonable picture quality by allowing for variable operating conditions (such as current duty cycle) for different LEDs.2. Description of the Robotic Spectroscopic HeadA photograph of the robotic platform is shown in Figure 1. The head can move along one horizontal axis (x-axis) and one vertical axis (z-axis). The pitch of its movement along each of the axis is 1 mm. Stepper motors are used for high precision movement with a speed of approximately 2” per second. The spectrometer head is attached with a custom fitting to the motor platform.The spectrometer used is an off-the-shelf USB4000 by Ocean Optics containing a 3648 element Toshiba linear CCD array for increased signal to noise. The wavelengths measured are a range of 200-1100nm, which equates to approximately a 1.4nm resolution. This device has a sensitivity of 130 photons/count at 400nm and 60 photons/count at 600nm.19th International Conference on Systems EngineeringFigure 1. A photograph of the roboticspectrometer headFigure 2. A photograph of the UNLV motorcontrollerThe motor platform is controlled with our custom motor controller, system shown in Figure 2. This motor controller allows for dual-axis control, with an extra backup driver in case of failure. This contains controller has a USB interface to communicate with our Windows based GUI software, and is driven by an Atmel Atmega2561 Microcontroller. There is sufficient isolation between the digital electronics and analog power electronics.Due to mechanical tolerances and minor variances in the assembly of the LED grid arrays, when the motor is instructed to move between LEDs, we cannot automatically assume that it will actually move exactly to the intended location . To address this issue, we employ a method of intensity-peak-seeking through an optical intensity feedback algorithm. This will guarantee that the spectrometer is accurately positioned during intensity measurements.Figure 3. Schematic diagram illustrating the spectrometer head position by peak detectionIn Figure 3, a schematic diagram illustrates the problem of positioning the spectrometer accurately in front of the LEDs. The arrow points the horizontal (x) direction, which corresponds the movement from one LED to the next. As the spectrometer head moves closer to the next LED, the intensity increases and then decreases if the motor overshoots the position of the spectrometer. When the intensity decreases, it indicates the previous location corresponds to the maximum intensity and that position can be used for making the intensity measurement. This procedure provides confidence in the accuracy of location of the spectrometer for intensity measurements in the x direction. Although this finds the peak intensity in horizontal direction, the spectrometer head may not be aligned with the location of the LED in the vertical direction (y axis) Additionally, the process of peak-seeking is implemented for the vertical direction also so that the spectrometer is accurately aligned with respect to both the horizontal and vertical directions in order to obtain the maximum intensity.Figure 4. A photograph of the UNLVpreprocessorThe UNLV motor controller controls the movement of the motor only. To process the spectrometer data and analyze the spectrum, a separate processor, called UNLV Preprocessor was developed by UNLV, which is shown in Figure 4. This preprocessor provides an interface to the USB4000 spectrometer (RS232 communications) and uses the intensity feedback to position the UNLV motor controller (FIGURE 5).Figure 5. A photograph showing thespectrometer placementInitial placement of the motors and spectrometer is essential. If the starting position is unknown, only a relative position can be assumed. Optical sensors are used to reset the motors to a default position at initial startup. This procedure is also implemented if the system goes awry to prevent damage to any parts. A photograph of the optical sensors is shown in Figure 6.Figure 6. A photograph of the optical sensorsWiring of the sensors is handled by routing a 14-bit bus, which we can tap into at any point in the bus for sensor input. This is shown in FIGURE 7Figure 7. A photograph of a 14-bit data busThe motor controller and preprocessor possess microcontrollers that must be programmed to operate properly. We have designed our own dual controller programming board which allows simultaneous writing code and programming from two different computers using the same hardware programmer. A photograph of the dual microcontroller is shown in FIGURE 8. The programmer is an improvement over the highly popular Atmel STK500which requires external power because it uses a serial port. Whereas our system draws its power from the USB ports and can program multiple processors. Additionally, it has an improvement with an optional single inline programming connection for breadboard based programming. This also has a 700kHz clock output which can be useful for certain functions.Figure 8. A photograph of the dualmicrocontroller programmerThe motors we use are unipolar stepper motors run with the option for half step or full step sequencing. We are using motors from Applied Motion, model HT34-487 shown in FIGURE 9. These motors are operated at 24V DC and can handle a max current of 6.3A as wired.Figure 9. A photograph of the stepper motorsWe are using dedicated power supplies from Mean Well (FIGURE 10). The power supply for the motor isa regulated 24V DC output with a max current of12.5A.. The power supply used for the digital logic is a Mean Well S-320-5 which has a regulated DC output of 5V and a max current of 50A.Figure 10. A photograph of the Mean Wellpower suppliesOnce the system is setup, a FPGA board or a specialized video source will pulse the LED for different lengths of time, and we can characterize each LED of each pixel. This data will be stored on a computer.Figure 11. UNLV custom graphical userinterfaceShown in Figure 11 is our custom made Graphical User Interface (GUI). There is an option to include a white LED in the measurement if desired. During the initial setup of the software, the user can select how the dimensions of the LED brick being measured, orientation of the colors, and spacing between pixels. This particular image shows an 8x8 LED brick including white LED. The currently measured LED is in the second row, fifth column over, blue LED. This is much easier than trying to interpret fast-scrolling text in terminal software. Each LED brick is expected to have a unique ID which is stored with the physical characteristics of the brick along with intensity information.Figure 12. UNLV motor controller schematics The motor controller does not use off-the-shelf motor drivers. We wanted to have the flexibility to write our own driver firmware and to be sure we could handle the power requirements. Figure 12 has the schematics of the motor controller which contains a logic processing unit, electrical isolation protection between the power drivers and the logic, and a USB interface to send or receive information.3. Results and DiscussionThe limiting factor in our measurement system is the time to acquire the intensity count and spectrum information. Measurement time is approximately 200ms per reading. This is because the Ocean Optics spectrometer acquires all 3648 pixels of intensity. For example, if we wish to receive wavelengths of exactly 480nm, 540nm, and 700nm, the spectrometer continues to measure the intensity of the entire spectrum with a resolution of 1,4 nm. Due to the long acquisition time, it is very important to minimize the time between measurements. A few ways to improve speed that we have implemented are: (a) increase the data-send speed to 115,200 baud (b) receive the critical wavelengths. Even with these changes, the speed of measurement is limited to about 5 measurements per second. The spectrometer has 16-bit resolution which allows for an intensity reading between 0 and 65,535. If the device reaches saturation, we can simply modify the distance between the spectrometer head and the LEDs under test.Figure 13. Spectrum data for 460nm blue LEDFigure 14. Spectrum obtained for fluorescentlighting4. Planned Future WorkWe would like to redesign the motor driver to implement microstepping functionality. This would improve the smoothness of the motor movement.We will also research the use of higher speed servo motors instead of stepper motors. It may be necessary to buy an off- the- shelf photometer, or design our own optical measurement system. These changes will help improve speed of measurement immensely.The software GUI needs to be modified to allow a user to have more control over the system. In particular, the user needs to modify the exact types of measurement rather than selecting a pixel, moving to that pixel and taking and logging a measurement.A spectrometer system is needed that can sample at a frequency of at least 60 Hz to be able to analyze live video isolated at a single pixel. There is also too much time taken to move the motors and we need a better mechanical test bed. There is still much work to be done to make this a commercial viable device, but the test results we have are very encouraging.5. ConclusionsWith the abundance of LED display systems, there is a need for a complete system that can optimize displays from an optical and electrical perspective at the individual light emitting diode level. Current plans are in motion to apply the design to a proposed university display.。
LED显示屏控制程序开发外文文献5
LED Driver with Self-Optimized Channel Voltage A Switch-Mode Voltage Regulator Optimizes an Active Current Regulator for a LED Driver.Jae-Hyoun Park*, Hyung-Do YoonGreen Energy Research CenterKorea Electronics Technology InstituteSeongnam, Koreajhpark@keti.re.krAbstract—A novel L ED driver with multiple L ED-channels is presented, consisting of an active current regulator and a switch-mode voltage regulator for each channel. The active current regulator means no current-sensing resistor and directly controls an L ED-current. The switch-mode voltage regulator optimizes the channel voltage by means of keeping a minimum voltage drop across the active current regulator to barely supply a desired current to the LEDs. This self-optimization can be independently achieved for each channel. The proposed driver is designed by 0.35ȝm 40V high voltage process. Simulation results show that when the voltage drop across the L EDs is different for each channel, the proposed LED driver can adapt the channel voltage to a threshold voltage for normal operation and regulate an LED-current to obtain desired luminous intensity. Roughly, the proposed driver has a power-conversion efficiency of above 85%.Keywords-component; LED driver, active current regulator, switch-mode voltage regulatorg, self-optimized channel voltageI.I NTRODUCTIONRecently, high-brightness LEDs have been extensively applied to back lighting for a liquid crystal display (LCD), flashlights for camera phones, automotive illuminations, traffic signals, lighting therapy, and general-purpose lighting because of their many advantages, such as high luminous efficiency and intensity, super longevity, low maintenance requirements, and safety for environment [1]-[9].The brightness of LEDs is directly proportional to their forward current not to their forward voltage. Namely, LEDs are current-driven devices. There are two reasons to drive them with a constant current: one is to avoid violating the absolute maximum current rating and compromising the reliability; the second is to obtain predictable and matched luminous intensity and chromaticity from each LED [1]-[4]. A simply method to guarantee that uniform brightness is obtained by each LED is to connect them in series. Series connection of LEDs, however, suffers from their cumulative forward voltage drop that finally restricts the number of LEDs in a channel. Even so, parallel connection of LEDs and/or LED channels is undesirable because current mismatch problems should be occurred by two electrical characteristics of an LED, one is the exponential voltage-current characteristic and the other is the negative temperature coefficient of the forward voltage drop. A straightforward approach for driving the paralleled multiple LED-channels is to independently regulate a current and/or a voltage for each channel, that is, an LED-current is regulated for an individual channel, as shown in Fig. 1 [1]-[3].The LED driver can be realized by linear or switch-mode type [1]. Compared with a switch-mode driver, a linear drivers, such as a low-dropout (LDO), are less expensive, smaller in area, lower noise, and easier to be used. The linear drivers, however, suffer from poor operating efficiency because the voltage drop across the linear driver cannot be minimized under all operating conditions. In more detail, the input voltage of the LDO linear driver should be designed considering the worst-case condition for the maximum forward voltage of the LEDs, to guarantee that the current of each LED channel is regulated in the entire temperature and current range. As a result, the LDO linear drivers should operate with poor efficiency when the connected LEDs have a below maximum forward voltage drop. This is suitable for battery-powered illumination fields such as automotive illumination which are sensitive to noise and electro-magnetic interference (EMI) [5]. On the other hand, the switch-mode drivers are common choices for a high-current or high-power LED driver because they can drive high output current with high power-conversion efficiency. This approach, however, has more complex, expensive, and noisy [1], [6].In this paper, a novel multi-channel LED driver which consists of an active current regulator and a switch-mode voltage regulator for each channel is proposed. The active current regulator is realized by linear type and directly controls an LED-current without a current-sensing resistor. The proposed driver makes a feature of self-optimization of thelinear current regulator by the switch-mode voltage regulator.Figure 1. Typical LED Driver with a current regulator in each channel.This work was supported by the IT R&D program of MKE/KEIT [2009-S-001-01, Development of Informative & Electronic Core Technology in Company Needs].II. C IRCUIT D ESIGNA. Design ConsiderationsThe linear and the switch-mode driver are both basically a kind of an output voltage regulator, and thus have to be converted to an output current regulator [5], [6]. In general, commercial products use a passive element, such as a sensing resistor, placed in series to the LEDs for the purpose of sensingthe LED-current and converting it to a feedback voltage for constant current control, as shown in Fig.2 [4]-[8]. However, this sensing resistor approach has some serious problems as high-brightness LEDs are widely used. One is power dissipation that increases in square rate to an LED-current [5]-[7]. As a driving current increased, this sensing scheme will dissipate higher power and further limit power efficiency. The second is accuracy of an LED-current and ease of use. This problem is also originated from power efficiency, as above-mentioned. To increase power efficiency, the feedback voltage which is a voltage drop across the sensing resistor should be lowered, typically below 300mV. For example, a certain driver has a feedback voltage of 250mV and should drive an output current of 350mA which is general with a high-brightness LED. In this case, a current sensing resistor should be set to 0.7 but the smallest resistance of a standard surface-mounted resistor is 1 . Therefore, we can simply select a 1 resistor or should connect several resistors in series and/or in parallel. The former can achieve ease of use but has inaccuracy of an LED-current, i.e. 250mA, and then undesired luminous intensity and chromaticity should be obtained. On the other hand, the later has design complexity but can obtain current accuracy and desired optical properties. Therefore, a advanced current regulating method has to be developed to meet the requirements for the LED driver such as efficiency, accuracy, ease of use, and so on [7], [9].B. Proposed LED DriverA block diagram of the proposed LED driver is shown in Fig. 3, which has four channels for parallel connection. The proposed LED driver consists of an LDO regulator for an internal bias, constant current control circuits with current-sink transistors, complimentary switching transistors with a controllogic and gate-drive buffers for switch-mode voltage regulators,Figure 2. Block diagram of a typical LED driver with a switch-moderegulator and a sensing resistor for a current regulation.a soft-start circuit, error amplifiers, comparators, a sawtooth waveform and clock generator, a pulse-width-modulation (PWM) generator, and a thermal shutdown circuit. As shown in Fig. 3, the proposed driver forms buck converters with external components, such as an inductor and a capacitor. The current-sink transistors and the complementary switching transistors are connected in series with each LED channel. It is possibleby controlling these transistors that a channel voltage and an LED-current are both independently regulated for an individual channel. The external capacitor C EXT and the external resistor R EXT determine a PWM frequency for dimming control and an LED current, respectively. The proposed driver is designed andsimulated by 0.35ȝm 2-poly 4-metal 40V high voltage process. A layout of the designed LED driver is shown in Fig. 4. Thechip area is 3mm by 1.8mm. Compared with a typical LED driver shown in Fig. 2, the proposed driver has the current-sink transistors, instead of theexternal sensing resistor and the dimming transistor, which compose the constant current control circuit. In a typical driver, the sensing resistor converts the LED current to the feedback voltage and regulates the LED current. But the sensing resistorhas some problems, as mentioned above. In the proposed LEDFigure 3. Block diagram of the proposed LED driver with a switch-modevoltage regulator and a self-optimized active current regulator.Figure 4. Layout of the designed LED driver.driver, however, the LED current is actively regulated using the constant current control circuit which is based on a current-mirroring circuit. The main idea of the proposed driver is as follows. The current mirroring circuit including the current-sink transistor can regulate the desired LED-current if and only if the current-sink transistor operates in a saturation region. In other words, the drain-source voltage V DS of the current-sink transistor should be enough high to saturate the current-sink transistor for normal operation of the proposed driver. Additionally, power consumption in the current-sink transistor should be minimized for high efficiency. Thus, it is desired that the V DS is always set to the minimum saturation voltage, regardless of a forward voltage drop across LEDs. Using a feedback of the V DS, the switch-mode voltage regulator can control the channel voltage which is equal to a sum of the cumulative forward voltage drop and the V DS. That is, the switch-mode voltage regulator self-optimizes the active current regulator in the proposed LED Driver.This proposed method may offer solutions for easy of use and current accuracy as the requirements for the LED driver. First of all, this method has relatively more freedom than the sensing resistor method to design the external resistor for a desired LED-current because there is scarcely restriction on the voltage across that resistor. This will be confirmed in the next chapter. Next, although the proposed driver should have the external resistor R EXT to bias the current-mirroring circuit, power loss in the R EXT could be neglected because the designed current-mirroring circuit has current gain of approximately 104, that is, the current through the R EXT is 10-4 times the LED-current. In the proposed driver, main power loss is occurred in the current-sink transistor. For given device parameters of that transistor, power loss should be minimized by the proposed self-optimization method. In order to improvement on power efficiency, therefore, the minimum saturation voltage V DS_sat of the transistor should be lowered, which is determined by process of a foundry service. For an ideal MOS transistor, the V DS_sat is zero, and then power loss in the current-sensing transistor should be zero and maximum power efficiency can be obtained.III.R ESULTS AND D ISCUSSIONA simulation result about the LED-current as a function of resistance of the external resistor is shown in Fig. 5. This simulation is done with only standard resistance of surface-mounted resistors. As shown in the result, the LED current is inverse proportion to resistance of the R EXT and can be set to 350mA, exactly 340mA, at 2.7k for a high-brightness LED as well as 20mA at 47k for a small LED. It is confirmed that the proposed method is easier to design the external resistor for the desired LED-current than the sensing resistor method.A simulation about self-optimization of the channel voltage is done by means of connecting a different number of LEDs, such as four, six, eight and ten, in series for each channel and observing the output voltage of the switch-mode regulator, the drain-source voltage of the current-sink transistor, and the LED-current through each channel, as shown in Fig. 6, Fig. 7, and Fig. 8, respectively. The simulation conditions are a supply voltage PVDD of 30V, a reference voltage V REF of 0.62V, inductance of the external inductor of 0.47ȝH, a switching frequency of the buck converter of 100kHz, and resistance of the external resistor of 15k for an LED current of 60mA. An LED which is SPICE-modeled and used in this simulation approximately has the forward voltage of 2.75V at the forward current of 60mA.As shown in Fig. 6, it is verified that the output voltage of the buck converter automatically goes to the sum of the voltage drop across the LEDs and the minimum saturation voltage. Delay of several ms and inflections of the waveforms are caused by a soft-start function. The more LEDs need the longer delay because the soft-start circuit makes the feedback voltage or the drain-source voltage V DS start from zero, as shown in Fig.7. In any number of LEDs, it should be confirmed that the drain-source voltage V DS goes to the reference voltage V REF or the minimum saturation voltage V DS_sat of 0.62V. This voltage is a little high because the 40V high voltage process used in this research is not optimized for the proposed method. It is sure that advance and optimization of the high voltage process can lower the minimum saturation voltage. It is also confirmed in Fig. 8 that the LED current is always regulated to 60mA inall cases.Figure 5. Simulation result about the LED-current as a function of resistanceof the external resistor R EXT.Figure 6. Simulated voltage waveforms at the output nodes of the switch-mode voltage regulators under a different number of LEDs for each channel.(a) four LEDs (b) six LEDs (c) eight LEDs and (d) ten LEDsFigure 7. Simulated waveforms of the drain-source voltage of the current-sink transistors under a different number of LEDs for each channel.(a) four LEDs (b) six LEDs (c) eight LEDs and (d) ten LEDsFigure 8. Simulatin results about the current through the LED under adifferent number of LEDs for each channel.(a) four LEDs (b) six LEDs (c) eight LEDs and (d) ten LEDsThe power-conversion efficiency of the designed LED driver is above 85% at the supply voltage of 30V, the output current of 60mA, and the switching frequency of 100kHz, even though these are not yet optimized conditions for the buck converter.IV.C ONCLUSIONSIn this paper, a novel multi-channel LED driver is proposed, consisting of an active current regulator and a switch-mode voltage regulator for each channel. The active current regulator directly controls an LED current using a current mirroring circuit and an external resistor for biasing. The switch-mode voltage regulator with integrated complimentary switching transistors and an external inductor forms a buck converter and optimizes the channel voltage by means of keeping a minimum voltage drop across the current-sink transistor of the current mirroring circuit to only regulate a desired LED current. This self-optimization can be independently achieved for each channel. The proposed driver is designed by 0.35ȝm 40V high voltage process. Self-optimization of the proposed driver is simulated by means of observing the output voltage of the switch-mode regulator for a different voltage drop across the LEDs for each channel. It is confirmed that the driver can self-adapt the channel voltage to the threshold voltage for normal operation and always regulate the LED current for desired luminous intensity. Roughly, the designed driver has a power-conversion efficiency of above 85% at the output current of 60mA. This self-optimization method, therefore, should meet requirements for an LED driver such as efficiency, accuracy, ease of use. It is concluded that the proposed LED driver is suitable for a high-brightness LED application as well as a small LED application without any restriction on current regulation.A CKNOWLEDGMENTThe authors would like to thank Mr. Yong-Seok Hahn and Yong-Suk Choi, the technical director and the chief engineer, respectively, of the mSilicon Co., Ltd., for their useful discussion and technical supports throughout this work.R EFERENCES[1]Y. Hu and M. M. Jovanoviü, “LED driver with self-adaptive drivevoltage,” IEEE Trans. Power Electron., vol. 23, no. 6, pp. 3116–3125, Nov. 2008.[2]Y. H. Fan, C. J. Wu, C. C. Fan, K. W. Chih, and L. D. Liao, “Asimplified LED converter design and implement,” presented at the 9th Joint Conf. Inf. Sci. (JCIS), Taipei, Taiwan, Oct. 2006.[3]S. Y. Tseng, S. C. Lin, and H. C. Lin, “LED backlight power systemwith auto-tuning regulation voltage for LCD panels,” in Proc. IEEE Appl. Power Electron. Conf. (APEC), pp. 551–557, Feb. 2008.[4]Maxim-Dalls Semiconductor, “Why drive white LEDs with constantcurrent,” Jun. 2004.[5]Y. Y. Lin, J. Zhang, X. C. Zou, and W. Li, “An efficiency-enhanced lowdropout linear HB LED driver for automotive application,” presented at IEEE Electron Devices and Solid-State Circuits Conf. (EDSSC), Hong Kong, China, Dec. 2008.[6]W. Y. Leung, T. Y. Man, M. Chan, “A high-power-LED Driver withpower-efficient LED-current sensing circuit,” in Proc. the 34th European Solid-State Circuits Conf. (ESSCIRC), pp. 354-357, Sept. 2008.[7]I. H. Oh, “An analysis of current accuracies in peak and hystereticcurrent controlled power LED drivers,” in Proc. IEEE Appl. Power Electron. Conf. (APEC), pp. 572–577, Feb. 2008.[8]X. Zou, K. Yu, Z. Zheng, X. Chen, Z. Zou, and D. Liao, “Dynamiccurrent limitation circuit for white LED driver,” in Proc. IEEE Asia Pacific Conf. Circuits and Systems (APCCAS), pp. 898-901, Dec. 2008.[9]G. Carraro, “Solving high-voltage off-line HB-LED constant-currentcontrol-circuit issues,” in Proc. IEEE Appl. Power Electron. Conf.(APEC), pp. 1316–1318, Feb. 2007.。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
毕业设计（论文）外文文献翻译文献、资料中文题目：大屏幕显示系统的研究文献、资料英文题目：The research of the large screendisplay system's文献、资料来源：文献、资料发表（出版）日期：院（部）：专业：班级：姓名：学号：指导教师：翻译日期： 2017.02.14译文：大屏幕显示系统的研究LED的发展随着计算机技术的高速发展，LED屏幕显示系统作为继电视、广播、报纸、杂志之后的“第五大媒体”正快速步入社会生活的各个方面。
它集微电子技术、计算机技术、信息处理技术于一体，可以将信息通过文字、图案、动画及视频四种形式显示出来。
与电视墙、磁翻板等媒体相比，LED大屏幕显示系统具有图案美观、色彩亮丽；图案、色彩变化丰富、快速；低功耗、长寿命、使用成本低、工作稳定可靠等特点。
它显示的图文视角大、视距远，因而已广泛应用于大型广场、商业广告、体育场馆、信息传播、新闻发布、证券交易；它还应用于工业控制和工业调动系统，便于把各种参数、报警点、工艺流程显示得更加清晰完美，可以满足不同环境的需要。
LED显示屏是一种利用计算机和复杂数字信号处理的电子广告宣传屏。
它的屏体部分由微处理器（主要是单片机）和驱动电路控制运行，显示的图像或文字由计算机编辑软件编辑获得。
由于LED显示屏这种新一代信息显示设备具有显示图案稳定、功耗低、寿命长等特点，而且它综合了各种信息显示设备的长处，并且克服了自身的不足，特别是由于一幅显示屏可以显示不同的内容，显示方式丰富。
所以在公共场合，它具有强烈的广告宣传和信息传递效果，日趋在固体显示中占主导地位。
LED显示屏的发展前景极为广阔，目前正朝着更高亮度、更高耐气候性、更高的发光密度、更高的发光均匀性、可靠性、全色化方向发展。
由不同材料的半导体组成能发出不同色彩的LED晶点。
目前应用最广的是红色、绿色、黄色LED。
而蓝色和纯绿色LED的开发已经达到了实用阶段。
LED显示屏的分类LED显示屏是多种技术综合应用的产品，涉及光电子学、半导体器件、数字电子电路、大规模集成电路、单片机及微机等各个方面，既有硬件又有软件。
LED 显示屏是作为广播、电视、报纸、杂志之后的又一新传播媒体。
目前LED显示屏根据使用场所不同，可以分为室外屏和室内屏两种，其主要区别是发光管的发光亮度不同。
而根据所显示的内容不同也可以分为图像屏和文字屏两种，图像屏可以显示图像以及多媒体，而文字屏则主要显示文字或简单的固定图像。
显示图像的多媒体室外屏是投资巨大(高达数百万)的大型高档设备，主要应用在大型公共场所、形象工程和一些重要场所。
LED显示屏的应用涉及到社会经济的许多领域，已经遍及交通、证券、电信、广告、宣传等各个方面。
L ED显示屏的发展趋势目前LED显示屏的显示向更高亮度、更高耐气候性、更高的发光均匀性、更高的可靠性、全色化、多媒体方向发展，系统的运行、操作与维护也向集成化、网络化、智能化方向发展。
二十一世纪的显示技术将是平板显示的时代，LED显示屏作为平板显示的主导产品之一将有更大的发展。
1．高亮度、全彩化蓝色及绿色超高亮度LED产品出现以来，成本逐年快速降低，使LED全彩色显示屏产品成本下降，推广速度加快。
同时，随着控制技术的发展和LED显示屏体稳定性的提高，全彩色LED显示屏的亮度、色彩、白平衡均达到比较理想的效果，完全可以满足户外全天候的环境条件要求，而且图像更清晰、更细腻、更亮丽。
2．标准化、规范化材料、技术的成熟及市场价格基本均衡之后，LED显示屏的标准化和规范化将成为LED显示屏发展的一个趋势。
近几年业内的发展中，几番价格回落调整达到基本均衡后，产品质量、系统的可靠性等将成为主要的竞争因素，这就对LED显示屏的标准化和规范化有了较高的要求。
行业规范和标准体系的形成，IS09000系列标准的应用，使LED显示屏行业的发展趋于有序。
3．产品结构多样化随着信息化社会的形成，信息领域愈加广泛，LED显示屏的应用前景更为广阔。
预计大型或超大型LED显示屏为主流产品的局面将会发生改变，适合于服务行业特点和专业性要求的小型LED显示屏会有较大提高，面向信息服务领域的LED显示屏产品门类和品种体系将更加丰富，部分潜在市场需求和应用领域将会有所突破，如公共交通、停车场、餐饮、医院等综合服务方面的信息显示屏需求量将有更大的提高。
涉及思路及工作原理本系统根据经典的电路设计思路，采用自下而上的设计方法，从显示板到驱动板，再到控制板，进行硬件编程，调试成功后接电源板，最后完成数据传输板与PC机相连接，进行PC软件编程，完成显示数据的生成、提取、处理、传输以及显示效果的实时控制。
每个模块采用8个LED点阵以行扫描形式点亮各行的红、绿、红绿灯，显示文字和图像。
LED点阵的驱动、译码、锁存等由控制板的数字电路负责。
其数据由单片机从存储器中读取，同时单片机采用中断方式，通过RS-232数据线与PC机进行双向通信，从PC机获取命令或数据，并按命令执行动作或者存储数据。
而PC机不但与多个单片机进行多机串口通信，还要负责文字录入和排版，生成点阵数据或者命令字，实现人机交互功能。
工作原理本文设计的大型LED显示屏由双基色点阵LED组合而成，采用逐行扫描的显示方式显示红、绿、黄三种颜色的任意点阵信息。
显示模块采用逐行扫描显示的方式，其控制系统以单片机AT89C52为核心，采用62256存储器作为数据存储器，利用锁存器74HC377和8组线驱动器2083A驱动8*8的LED显示模块，同时开放串口中断与上位PC机进行多机通信。
通过对单片机编程实现显示屏的多种动画模式显示：向左滚屏，向右滚屏，向上滚屏，向下滚屏，向左上滚屏，向右上滚屏，向左拉幕，向右拉幕，向上拉幕，向下拉幕，向右移，从左向右、依次点亮，从中间到两边、依次点亮。
动画速度可调：分为100档，最低为1速，最高为100速。
图案颜色多样：背景无色、文字红/绿/黄色，背景红色、文字无/黄/绿色，背景绿色、文字无/黄/红色，背景黄色，文字无/红/绿色。
另外，还增加了几十种霓虹灯效果动画。
PC机上的显示控制软件可以实现汉字录入、字体选择、字号更改等功能，并且在进行数据处理后，可以在左侧模拟演示整体效果，同时“所见即所得”的显示在下方预览区域。
另外，该控制软件还具有文本选定、鼠标定位、坐标追踪、时间日期等附加功能。
PC机通过RS-232接口实现与显示部分的单片机的通信，利用单片机串口中断实时接收和发送数据信息。
在系统设计中还兼顾了单片机的抗干扰能力，有效地提高了系统运行的可靠性。
发光二级管特性发光二极管(light emitting diode,LED)，是一种把电能变成光能的特种器件，当电流达到门限电流时，发光二极管导通，随着电流的通过，产生可见光。
发光二极管的结构主要由PN结芯片、电极和光学系统构成。
当在PN结上加以正向电压之后，P区的空穴注入至N区，N区的电子注入至P区，相互注入的电子与空穴相遇后即产生复合，这些少数载流子在PN结的注入和复合中产生辐射而发光。
它是自发辐射发光，不需要较高的注入电流产生粒子数反转分布，也不需要光学谐振腔，发射的是非相干光。
描述LED的特性有许多参数，这些参数之间的关系呈现非线性。
因此，用特性曲线来描述这些关系，在工程应用中更具有使用价值。
LED器件的驱动从LED器件的发光机理可以知道，当向LED器件施加正向电压时，流过器件的正向电流使其发光。
因此LED的驱动就是要使它的PN结处于正向偏置，同时为了控制它的发光强度，还要解决正向电流的调节问题。
具体的驱动方式有直流驱动、恒流驱动、脉冲驱动和扫描驱动等，本系统中LED器件的驱动为扫描驱动。
1．直流驱动。
直流驱动是最简单的驱动方法。
LED的工作点由电源电压VCC，串联电阻R和LED器件的伏安特性共同决定。
这种驱动方式适合于LED器件较少，发光强度恒定的情况。
例如公交车上使用的用来固定显示“XX路”字样的显示屏。
2．恒流驱动。
由于LED器件的正向特性较陡，加上器件的分散性，使得在同样电源电压和同样限流电阻的情况下，各器件的正向电流并不相同，从而引起发光强度的差异。
若对LED器件进行恒流驱动，只要恒流值相同，发光强度就比较接近。
晶体管的输出特性具有恒流特性，所以可以用晶体管驱动LED。
3．脉冲驱动。
利用人眼的视觉惰性，采用向LED器件重复通断电的方式使之点燃，就是脉冲驱动方式。
脉冲驱动主要有两个方面的应用：扫描驱动和占空比驱动。
扫描驱动的主要目的是节约驱动器，简化电路。
采用这种方式时应该注意两个问题:确定脉冲电流幅值和选择重复频率。
首先，要想获得与直流驱动方式相当的发光强度，脉冲驱动电流的平均值就应该与直流驱动的电流值相同。
4．扫描驱动。
扫描驱动通过数字逻辑电路，使若干LED器件轮流导通，用以节省控制驱动电路。
LED显示屏将发光灯按行按列布置，驱动时也按行按列驱动。
在扫描驱动方式下可以按行扫描，按列控制；也可以按列扫描，按行控制。
所谓“扫描”的含义，就是指一行一行地循环接通整行的LED器件，而不管这一行的哪一列的LED器件是否应该点亮，具体某一列的LED器件是否应该点亮，则由所谓的列控制电路来负责。
外文资料原文:The research of the large screen display system'sLed developmentAlong with computer technology's high speed development, LED (Light Emitting Diode) the screen display system takes after the television, the broadcast, the newspaper, the magazine “the fifth big media” marches into the social life fast each aspect. Its collection microelectronic technology, the computer technology, the information processing and management technology in a body, may the information through the writing, the design, the animation and the video frequency four forms demonstrates. With media and so on bank of television monitors, magnetism vane compares, the LED large screen display system has the design to be artistic, the color is sharp; The design, the color change are rich, are fast; The low power loss, the long life, the use cost low, work stably reliable and so on characteristics. It demonstrated the chart article angle of view is big, the apparent distance is far, thus has widely applied in the large-scale square, the commercial advertizing, the sports complexes, the information dissemination, the news issue, the securities trading; It also applies in the industrial control and the industry reassignment system, is advantageous each kind of parameter, the alarm point, the technical process demonstrates clearly perfect, may satisfy the different environment the need. The LED display monitor is one kind of use computer and the complex digital signal processing electron advertisements propaganda screen. Its screen body part by the microprocessor (is mainly monolithic integrated circuit) and the driving circuit control movement, demonstrated the image or the writing obtain by the computer edition software editor. Because the LED display monitor this kind of new generation information graphic display device has the demonstration design to be stable, the power loss is low, life long and so on characteristics, moreover it synthesized each kind of information graphic display device's strong point, and has overcome own insufficiency, because specially a display monitor may demonstrate that the different content, the display mode is rich. Therefore in the public area, it has the intense advertisements propaganda and the information transmission effect, already in the solid demonstrated day by day occupies the dominant position. The LED display monitor's prospects fordevelopment are extremely broad, at present toward the high luminance, a higher weather fastness, the higher luminous density, the higher illumination uniformity, the reliability, the panchromatic direction is developing. Is composed of the different material's semiconductor can send out the different color the LED crystal spot. At present what applies is broadest is red, the green, yellow LED. But the blue color and the pure green LED development had already achieved the practical stage.LED display monitor's classificationLED display monitor's classified LED display monitor is many kinds of technical synthesis application product, involves photoelectronics, the semiconductor device, the digit electronic circuit, the large scale integrated circuit, the monolithic integrated circuit and the microcomputer and so on each aspect, both has the hardware and to have software. After the LED display monitor is takes the broadcast, the television, the newspaper, the magazine another new communication media. At present the LED display monitor basis uses the place to be different, may divide into the outdoor screen and the indoor screen two kinds, its main difference is photo tube's illumination brightness is different. But acts according to the content which demonstrated different also to be possible to divide into the image screen and the writing screen two kinds, the image screen may the display image as well as multimedia, but writing screen main demonstration writing or simple fixed image. Display image's multimedia outdoor screens are the investment huge (reaches as high as several millions) the large-scale upscale equipment, main application in large-scale public place, image project and some important places. The LED display monitor's application involves to social economy many domains, already spread the transportation, the negotiable securities, the telecommunication, the advertisement, the propaganda and so on each aspect.LED display monitor's trend of developmentAt present the LED display monitor's demonstration to the high luminance, a higher weather fastness, the higher illumination uniformity, a higher reliability, the panchromatic, the multimedia directions develops, system's movement, the operation and the maintenance also to the integration, the network, the intellectualized direction develop. The 21st century's display technology will be the panel display time, theLED display monitor takes one of panel display leadership products to have a bigger development.1. since the high luminance, entire color blue color and the green superelevation brightness LED product has appeared, the cost reduces fast year by year, causes the LED entire colored display monitor product cost to drop, the promoted speed speeds up. At the same time, along with control technology's development and the LED display monitor body stable enhancement, the entire colored LED display monitor's brightness, the color, white balanced achieves the quite ideal effect, definitely may satisfy the outdoors all-weather environmental condition request, moreover the image is clearer, is more exquisite, is sharper.2. after standardization, standardized material, technology mature and market price basic balanced, the LED display monitor's standardization and the standardization will become a tendency which the LED display monitor develops. In recent years industry in development, after several price recedes the adjustment achieves basically balanced, the product quality, the system reliable and so on will become the main competition factor, this had the high request to the LED display monitor's standardization and the standardization. Profession standard and standard system's formation, IS09000 series standard application, causes the LED display monitor profession the development tends the order.3. the product mix diversification along with the informationization society's formation, the information field is even more widespread, the LED display monitor's application prospect is broader. It is estimated that large-scale or the ultra-large LED display monitor will have the change for the mainstream product's aspect, will suit can have in the service industry characteristic and the specialized request small LED display monitor enhances greatly, will be richer face the information service domain's LED display monitor product class and the variety system, the part potential market demand and the application domain will have the breakthrough, like the mass transit, the parking lot, the dining, the hospital and so on comprehension service aspect's information display monitor demand will have a bigger enhancement.Involves the mentality and the principle of workThis system basis classics' circuit design mentality, uses the design method from bottom to top, from the display panel to the actuation board, arrives at the control panel again, carries on the hardware programming, after debugging successfully, receives a telegram the source plate, finally completes the data transmission board and PC machine connects, carries on the PC software programming, completes the demonstration data the production, the extraction, processing, the transmission as well as the demonstration effect real-time control. Each module uses 8 LED lattices to lighten each line by the line scan form red, green, the traffic light, the demonstration writing and the image. The LED lattice's actuation, the decoding, the lock save and so on to be responsible by control panel's digital circuit. Its data reads by the monolithic integrated circuit from the memory, simultaneously the monolithic integrated circuit uses the interrupt mode, carries on the two-way communication through the RS-232 data line and PC machine, from the PC machine gain order or the data, and carries out the movement or the stored datum according to the order. Not only but PC machine carries on many machine serial port correspondences with many monolithic integrated circuits, but must be responsible for the writing input and the typesetting, the production lattice data or the order character, realize the man-machine interaction function.Principle of work this article designs the large-scale LED display monitor becomes by the double primary color lattice LED combination, uses the line-by-line scanning the display mode to demonstrate red, green, the yellow three kind of color random lattice information. The display module uses the line-by-line scanning demonstration the way, its control system take monolithic integrated circuit AT89C52 as a core, uses 62256 memories to take the data-carrier storage, actuates 8*8 using latch 74HC377 and 8 group of line driver 2083The LED display module, simultaneously opens the serial port interrupt and superior PC machine carries on many machine correspondences. Through realizes display monitor's many kinds of animation pattern to the monolithic integrated circuit programming to demonstrate: Rolls the screen toward left, rolls the screen toward right, rolls the screen upwardly, rolls the screen downward, on rolls the screen toward left, on rolls the screen toward right, to the Zola curtain, pulls the curtain toward right, pulls the curtain upwardly,。