最新刊期
期 1 ， 2009
- 摘要：A general shape of biaxial nematic liquid crystal molecule was abstracted into three perpendicular rods. Using superposition of rod-to-rod interaction energy, the total interaction energy of liquid crystal system was derived. Expanding the total energy into a power series of directors distortion upto second order term, 12 rotational invariants related to directors distortion were obtained and the elastic energy density of the system in Saupes form was derived. The corresponding 12 elastic constants were expressed in explicit forms of molecular structure, and the relationship between 9 elastic constants of simple distortions and molecular rod lengths were discussed. When the molecule is non-cylindrical, system becomes biaxial, the molecular rod length along non-distortion director (ξ) makes no contribution to elastic energy, while the two rod lengths perpendicular to ξ contribute both to elastic constants. This elastic constant is determined by the square of their difference. Since this difference is related to the non-cylindrical symmetry, the stronger the non-cylindrical symmetry is, the larger the elastic constant is. When this difference is zero, the molecule is cylindrical, the elastic constants are reduced to those of uniaxial nematics.关键词：biaxial nematic liquid crystal;elastic constants;directors distortion
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发布时间：2020-08-12 - 摘要：The mesomorphic properties of two series of fluorine substituted liquid crystals containing three rings were systematically characterized to investigate their phase transition behavior using differential scanning calorimetry(DSC), microscopy heat analysis and polarizing optical microscopy(POM). The results show that all the compounds except 2CPPF3 and 4CPPF3 possess mesomorphism. Typical textures of smectic and nematic phase were observed. The influence of terminal alkyl, core structure and the number of fluorine substituents on the temperature of phase transition was discussed.关键词：liquid crystal;mesomorphism;smectic phase;nematic phase;texture
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发布时间：2020-08-12 - 摘要：At present liquid crystal adaptive optical system can not meet the requirement of correcting atmospheric turbulence frequency (＞40 Hz), which is mainly limited by response time of liquid crystal in LCOS (10~20 ms), meanwhile, phase modulation range should exceed 1λ. Hence the urgent need is to develop new nematic liquid crystal of fast response and high birefringence. This paper summarized general rules which impact the viscosity and birefringence of liquid crystal, on this basis, two liquid crystal molecules with low-viscosity, high birefringence were designed. Using the simulation of the AM1 semi-simulation quantum chemistry calculation, the values of Δn and Δζ were predicted. Simulation results showed that the two liquid crystal structure satisfied the requirements of adaptive system well.关键词：fast response;high birefringence;nematic;liquid crystal
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发布时间：2020-08-12 - 摘要：Liquid crystal (LC) alignment layer is one of the key materials of liquid crystal display (LCD). At present, the effect of polyimide (PI) structure on LC pretilt angle has been investigated widely, but the study on effect of additive on the pretilt angle was less. In this paper, pyromellitic dianhydride (PMDA), 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), 4 benzeneamine,4-hexyloxy-biphenyl-3',5'-diaminobenzoate, and additive ADD-34 were used to synthesize four PIs. The uniform LC molecule alignment induced by PI alignment films was confirmed by polarized optical microscope. It was found that the PI with ADD-34 possesses solvent resistance. LC pretilt angle increased firstly and then decreased with the increase of ADD-34 content in PI.关键词：liquid crystal alignment layer;polyimide;additive;pretilt angle
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发布时间：2020-08-12 - 摘要：Chiral dopants play an important role in liquid crystal displays, which can convert nematic phase to cholesteric phase. This article briefly introduced the development of chiral dopants and analyzed the requirement of chiral dopants for various modes. The emphasis placed on chiral dopants used in TFT and cholesteric liquid crystals displays. The relationship between the HTP values and structure was summarized,which will lay a theoretical foundation for the design of new chiral dopants.关键词：chiral dopants;HTP;progress
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发布时间：2020-08-12 -
Comparison of Optical and Electrical Properties of ZnS/Porous Silicon and ZnO/Porous Silicon Systems
摘要：ZnS films and ZnO films were prepared on porous silicon (PS) substrates with same porosity by pulsed laser deposition (PLD), and the optical and electrical properties of ZnS/PS and ZnO/PS systems were compared at room temperature. The results showed that, there was a broad photoluminescence band from 450 nm to 700 nm in the visible region of both ZnS/PS and ZnO/PS composites, exhibiting intensive white light emission. However, the white light emission performance of ZnS/PS composite was better than that of ZnO/PS composite. Based on the I-V characteristics, ZnS/PS heterojunction exhibited the rectifying junction behavior, but the I-V characteristic of the ZnO/PS heterostructure was different from that of the common diode, whose reverse current was not saturated.关键词：white light emission;photoluminescence;I-V characteristic;ZnS;ZnO;porous silicon- 17
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发布时间：2020-08-12
Material Physics & Chemistry
- 摘要：The key factors which limit plasma display panel (PDP) development are luminous efficiency, power consumption and cost. The research and improvement about cell structure, discharge mechanism, drive technology, and image procession are introduced. The cell structure supposed of PDP is introduced and discussed when the luminance efficiency reaches to 5 lm/W and 10 lm/W. And luminance, power consumption, the architecture of drive circuit system, especially for the cost are also discussed and forecasted.关键词：plasma display panel;cell structure;luminous efficacy;driving method;image processing
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发布时间：2020-08-12
paper
- 摘要：Using standard photolithography, patterned carbon nanotube line arrays were fabricated on silicon substrates by thermal chemical vapor deposition. Scanning electron microscopy and Raman spectroscopy were used to characterize the structure of the carbon nanotubes. The carbon nanotubes were very uniform and about 50 nm in diameter and 2 μm in length. The Raman spectrum showed that the carbon nanotubes were multi-walled carbon nanotubes. Field emission characteristics of the samples were characterized. It was found that the non-patterned carbon nanotube films, 10 μm and 2 μm size carbon nanotube line arrays field emission characteristics were gradually improved with turn-on field of 3 V/μm,2.1 V/μm,1.7 V/μm and emission current density at applied electric field 3.67 V/m were 2.57 mA/cm2,4.65 mA/cm2,7.87 mA/cm2,respectively. The reasons may attribute to the field-screening effect and edge effect by analyzing the experimental results.关键词：carbon nanotube;line array;thermal chemical vapor deposition;field emission characteristic
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发布时间：2020-08-12 - 摘要：Polymer dispersed liquid crystal (PDLC), consisting of low molecular liquid crystal dispersed in a polymer matrix, is a kind of film-formation material with excellent electro-optical properties. In this paper, PDLC films were prepared by photo-polymerization induced phase separation (PIPS) which was initiated by macro-iniferter agent prepared by atom transfer radical polymerization. It was found that the macro-iniferter was an effective way to improve the electro-optical properties of PDLC films. In addition, the properties of PDLC could also be adjusted through the curing time. It is found that as the curing time increase,the contrast ratio and the driving voltages of the films increase, while the memory effect significantly decreases.关键词：polymer dispersed liquid crystal films;atom transfer radical polymerization;polymerization induced phase separation;electro-optical properties
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发布时间：2020-08-12 - 摘要：ZnO : Al (ZAO) thin films based on Al doped ZnO ceramic target were prepared on slide glass substrates by DC magnetron sputtering at room temperature. The effects of Al doping content and sputtering parameter on electrical and optical properties of ZAO thin films were investigated. The experimental results show that both the Al content and process parameters have a great influence on electrical property. When the Al content is 3%, the sputtering power is 100 W, the argon gas pressure is 1.5 Pa, ZAO thin films have a lowest resistivity of 1.4×10-3 Ω·cm. The Al doping content and process parameters had a little influence on transmittance, and the average transmittances of ZAO thin films were from 86% to 90%, but the absorption edge has a blue shift with the increase of doping level and argon gas pressure. According to the analyses of FOM (figure of merit ) of ZAO, an argon pressure of 0.6~2.0 Pa is appropriate for ZAO thin films deposited by DC magnetron sputtering at room temperature.关键词：ZAO;transparent conducting thin films;electrical and optical properties;magnetron sputtering
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发布时间：2020-08-12 - 摘要：A polymer stabilized ferroelectric liquid crystal device (PSFLCD) was fabricated using thiol and acrylate in which the amount of monomer was 4%. When thiol added to acrylate, the chain-growth homopolymerization of the acrylate changed into the step-growth mechanism of a thiol-acrylate polymerization. For thiol-acrylate polymerizations, the conversion of ene functional groups was up to 84% greater than the conversion of 30％ by acrylate polymerizations. The amount of monomer in the ferroelectric liquid crystal(FLC) after polymerization is lower. In the device the polymer-net parallels the rubbing direction, A PSFLCD with V-shaped electro optical characteristics,fast respond time,high contrast ratio and good stability was fabricated.关键词：polymer stabilized ferroelectric liquid crystal;thiol;high conversion
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发布时间：2020-08-12 - 摘要：Transparent conducting zirconium-doped zinc oxide (ZZO) films with high transparency and relatively low resistivity have been successfully prepared by direct current magnetron sputtering at room temperature. The effect of sputtering power on the structures, morphologies and optic-electronic properties of ZZO films was investigated in detail. The experimental results show that sputtering power is an important factor to the crystal structure and electronic properties of ZZO films. All the deposited films are polycrystalline with a hexagonal structure and a preferred orientation perpendicular to the substrates along the c-axis. At the optimal sputtering power of 115 W, the lowest resistivity achieved is 1.9×10-3 Ω·cm with a hall mobility of 18.7 cm2·V-1·s-1 and a carrier concentration of 2.07×1020 cm-3. All the films present a high transmittance of above 92% in the visible range. ZZO films with high transparency and relatively low resistivity deposited at room temperature will be widely used in microelectronic devices such as liquid crystal display, film solar cells and so on.关键词：ZnO : Zr films;transparent conducting films;sputtering power;magnetron sputtering
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发布时间：2020-08-12 - 摘要：Organic thin film transistors (OTFTs) were modified by silane coupling agents- octadecyltrichlorosilane (OTS) with different thicknesses of CuPc. Comparing with different thicknesses of CuPc layer of 15 nm、40 nm and 80 nm, the 40 nm CuPc devices have the best performance on mobility. The performance of OTFTs that were modified by OTS has been investigated. Electrical parameters such as carrier mobility and threshold voltage by field effect measurement have been calculated. For OTFT based on the 40 nm CuPc, the field-effect mobility is 4.3×10-3 cm2/V·s and threshold voltage is -9.5 V.关键词：CuPc;thickness of semiconductor;mobility
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发布时间：2020-08-12 - 摘要：In the experimentation, the blue OLED with 9,10-di-(2-naphthyl) anthracene (ADN)as light-emitting subjectivalization was fabricated. It is found that the performances of devices are effected by the thickness of AND.When the ratio of AND/Alq3 thickness is 4 : 3,and the thickness of AND is 40 nm,the open voltage of devices is lower and the characteristic of luminescence is improved. In addition,when the TBP is doped in devices,the energy level structure is changed. For this reason the efficiency of electronic injection is improved and hole export keeps off state.So the recombination rate of exciton is improved.It is also found that scale of the TBP doping has a best level.When the scale level is 2%,the characteristic of luminescence and color purity quotient of the devices are best.关键词：blue OLED;ADN;TBP;color purity quotient
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发布时间：2020-08-12 - 摘要：The morphology of polymer dispersed liquid crystals (PDLC) has a great influence on their electro-optical properties, so there is an important academic value to adjust the morphology of PDLC through the different curing conditions. In this paper, reversible addition fragmentation transfer (RAFT) polymerization was employed to prepare PDLC in the process of polymerization induced phase separation (PIPS). The effects of RAFT-PBA concentration and curing time on morphology and OFF-state transmittance of PDLC were studied. It was found that the OFF-state transmittance of PDLC decreases with increasing the curing time, and then keeps constant. The more RAFT-PBA there are in the PDLC films, the bigger the radius of the liquid crystal droplets become. The lowest OFF-state transmittance was achieved when the concentration of RAFT-PBA in the systems was 15%.关键词：polymer dispersed liquid crystals;RAFT polymerization;glass transition;morphology
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发布时间：2020-08-12
Device Technology & Physics
- 摘要：Flat Fluorescent Lamps(FFL)with dielectric barrier discharge is a new type of flat light source, which has a cheerful prospect as backlight for LCD. In this paper, the pin structure and internal structure of SG3525 were introduced, moreover, based on this chip, a method of designing the driving circuit for FFL was proposed. A flyback inverter was adopted in this design. A series of peak pulses with a width of 3~4 μs and an amplitude of 2 000~2 500 V were created, when the input direct current voltage was 80~100 V. The circuit has been proved on a FFL prototype, the results show that this design method has some advantages such as easy, flexible, high efficient and cheap. Moreover, the FFLs brightness of 6 000 cd/m2 and brightness uniformity of above 80% can be achieved by the circuit.关键词：flat fluorescent lamps;dielectric barrier discharge;driver circuit;flyback inverter;backlight
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发布时间：2020-08-12 - 摘要：A kind of design and implementation of intelligent infrared remote controller based on 51 series MCU was presented. The remote controller with self-study function which is implemented by pulse width measuring, has the ability to receive and learn the code of infrared instructions from others and repeat it again. So we can use only one remote controller instead of several to control many different electro-appliances. In this paper, infrared coding principle was briefly described, the focus is given to a remote control system hardware and software flow structure, test results show that intelligent remote control is easy to operate, works stably, and can receive data accurately.关键词：infrared;intelligent remote control;coding;decoding;AT89S52
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发布时间：2020-08-12 - 摘要：A source driver structure used for small or medium size TFT-LCD was proposed, and the rail to rail output buffer of source driver was mainly studied and designed. This structure is especially suitable for the future development for large size TFT-LCD panel, and satisfies the driver ICs requirements for both area and function. This paper mainly describes the design of the rail-to-rail output buffer based on the proposed structure. The Hspice simulation results show that the gain margin is 90.7 dB and phase margin is 75°, and the static current is 1.1 μA, the buffer area is 400 μm2,which satisfies the system requirements.关键词：TFT-LCD;source driver;rail-to-rail
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发布时间：2020-08-12 - 摘要：The driving circuits of 16×16 LED Chinese dot-matrix display have been designed based on Proteus software, an embedded system simulation flat. The hardware circuits include three parts: AT89C51, driving circuits of row and column and LED display. The software functions were realized by assembly language after dot-matrix made. The physical circuits have been welded and the right dot-matrix display was realized. The results show the Proteus software application is an important practical value in the design of MCU, which will greatly shorten the development cycle and save development costs.关键词：Proteus;MCU;dot-matrix;LED display
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发布时间：2020-08-12 - 摘要：As a new traffic guiding panel, LED light ribbon traffic guiding panel appears in recent years. On the panel,static text and route segment are shown to indicate outline and direction of roads. Traffic condition of roads, such as block, smooth and congestion are expressed by different LED colors: red, green and yellow. Control system of panel consists of an industry computer and many LED light ribbon display controllers, which all connect to RS-485 bus. The system adopts half-duplex mode and self-defined communication protocol. This paper chiefly presents design and implementation for light ribbon display controller. Each controller mainly composes of MCU, CPLD and RAM. MCU performs the task of producing display data and dealing with communication, CPLD accomplishes gray display that same color has same gray. Run length compress code is employed to ensure refreshing LED light ribbon quickly. Visiting conflict that MCU and CPLD visit the same RAM in same time can be avoided by applying interruption and software timing strategy. A method which MCU visits RAM assisting by CPLD leads to simplifying PCB wire arrangement. 16 bit constant current driver MBI5027 with function of LED open circuit error detecting makes LED detecting carry out only by software without circuit.关键词：LED light ribbon;same color with same gray;run length encoding;LED open circuit error detecting
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发布时间：2020-08-12 - 摘要：Design of LCD-HS12232 dot-matrix LCM based on DSP-TMS320F2812 and its application interface are introduced. The design method of hardware interface and software program are provided. Modular program design of showing section is proposed, and its application in device monitoring system is discussed. Specific issues of multi-task operating efficiency in the design process are solved. Structured design system has convenient user interfaces and can be transplanted to many DSP control and data handling system.关键词：TMS320F2812;LCD;modular design;interface design
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发布时间：2020-08-12 - 摘要：An innovative multifunctional and integrative analog camera system is designed in this paper, which implements zoom control and aperture control with FPGA. The design utilizes an improved gray scale differential algorithm as focusing evaluation function and utilizes a kind of search strategy to control the remove of step-motor, so the image can be auto-focused.关键词：FPGA;step-motor;auto-focus;aperture control
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发布时间：2020-08-12
Driving & Controlling
- 摘要：A new imaging system is designed by using an interline transfer CCD ICX415AL as sensor which is produced by Sony corporation and greatly improve the SNR of system . CCD imaging system uses special signal processing chip-CXA1310AQ making output signal to meet the standard of PAL/CCIR. It can be used with TV and computer which has video card as a display terminal. On the basis of introducing the structure and characteristics of CCD ICX415AL, the circuits of timing sequence and driver for sensor were designed. CCD works in field readout mode which can be realized as binning-technology in vertical direction and the noises of video signal are filtered by Correlated Double Sampling (CDS), the signal-to-noise ratio of system was enhanced. The system takes Field Programmable Gate Array (FPGA) as the key device. The CCD driving clock, clock control of data acquisition and video signal process were accomplished by the module design method from top to bottom.
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发布时间：2020-08-12 - 摘要：According to geometry model of the atmosphere back-scattering, an approximately expression of atmosphere back-scattering accumulative effect was deduced in this paper. The result showed that 80% of the backscattered flux of the receiver come from those particles inner 50 m away from the receiver. Then, a new method of dealing with the backscattered light was presented by using a double passage optical receiver. The simulation result proved its good effects in improving image quality. The construction of the double passage receiver was simple and it can be easily realized.关键词：active imaging;atmosphere back-scattering;analysis and treatment
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发布时间：2020-08-12 - 摘要：With the development of computer and graphics technology,the cockpit instruments have brought about a great challenge to the quality of the graphics. As hardware system using grating graphics display system, there are saw tooth-shaped distortion in compass screen when it rotates owing to the restrictions of the grating scan display. Based on this problem, by analyzing the causes of the aliasing, using a method of arithmetic of Bresenham to get rid of it,the effect of anti-aliasing has been proved obviously. With the application of the symmetry of line and circularity, the speed of the generation of a whole compass screen is highly advanced.关键词：aliasing;arithmetic of bresenham;symmetry
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发布时间：2020-08-12 - 摘要：Regarding of the characters of liquid crystal products, the non-contact inspection techniques for surface liquid crystal residues were studied. A novel edge-extraction algorithm based on iterative threshold segmentation method and mathematical morphology was proposed, which could find out the shape and edge of the liquid crystal residue. First, the original image was divided into several sub-images according to coordinate. Then, the iterative threshold segmentation was applied to the sub-images, and the multi-scale structural elements were used to detect the image edge. Finally,they were synthesized in a weighting way so as to form the edge, and the effect of noise on edge-extraction was analyzed in theory. The experimental results indicated that the method could suppress noise and have much stronger ability to preserve edge details, provide accurate and closed region contours, which lays a good foundation for defect feature extraction and selection.关键词：LCD;iteration method;edge detection;multi-scale morphology
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发布时间：2020-08-12
Imaging Technology & Image Processing
- 摘要：As the terminal display of multimedia facilities, the luminance uniformity of LED display screen is an important factor for display quality. In order to guide the R&D and production of LED display panel, an object and exact evaluation for LED luminance uniformity is necessary. In this paper, on the basis of the exiting methods, an evaluation method based on gray histogram has been raised. In this method, the luminance information of LED display penal is obtained by CCD image sensor, with digital image processing technology and statistical knowledge, the histogram is fitted by normal distribution curve. The luminance uniformity is evaluated by standard deviation, and it is proved to be fitted with subjective method.关键词：LED display panel;gray histogram;CCD image sensor;normal distribution;standard deviation
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发布时间：2020-08-12 - 摘要：Due to different situations requiring different uniform irradiance distribution, light sources with multiple LEDs become the preferred choice. So designing LED arrays for uniform irradiance is an essential problem. According to analyzing several typical configurations of LED illumination modules, the equations and formulas were established and the limit distance between LEDs was simulated with considering each single LED as a nonideal Lambertian emitter. From the result of simulation we can get the uniform irradiance in the distance of LEDs limit situation. Luminous intensity of center placement would abate, while the distance of LED increases; the increasing distance between the LED arrays center and the irradiance plane leads to the slacking down of the center irradiance.关键词：light-emitting diodes;LED arrays;illumination uniformity
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发布时间：2020-08-12
Test & Evaluation
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