最新刊期
期 5 ， 2015
- 摘要：Photoalignment technology is a kind of contactless method of aligning liquid crystal by using polarized light. It possesses many advantages, e.g., non-contamination, non-electrostatic charges, easy to realize multi-domain aligning even in a tiny fine area, and etc. Thus, it has attracted more and more attentions of the researchers all over the world. The review describes the status of the studies and the recent achievements in the field of photoalignment of liquid crystals, and it briefly illustrates the fundamental working principle of photoalignment technique and mechanisms of liquid crystal photoalignment materials. In particular, we concentrate on a recent approach of the photoinduced reorientation of azo-dyes, and some recent applications of photoalignment technology in aspects of (1) curved and flexible substrates, (2) optical data processing and high spatial resolution optical processing system, (3) liquid crystal optical elements with sophisticated geometric patterned alignment, (4) 3D ORW and ferroelectric liquid crystal displays, (5) optical filter and (6) other photoalignment materials, will be introduced.关键词：liquid crystal;photoalignment;anisotropic;polarized light;azo-dye
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发布时间：2020-08-12
Invited Paper
- 摘要：In order to realize the fabrication of the OLEDs by solution-processing, synthesis and application of highly soluble organic electroluminescent materials is one of the important ways. In the present work, a ligand containing a structural moiety of 4'-n-propyl-(1,1'-bicyclohexyl)-4-difluorophenyl commonly used in liquid crystal molecules and its iridium complex, Ir(cfpp)2(acac) (cfpp=2-[2,3-difluoro-5-(trans, trans-4"-n-propyl-(1",1'-bicyclohexyl)-4'-yl)phenylpyridine); acac=acetylacetonate) were synthesized. The synthesized iridium complex was used as a green light-emitting dopant material with 2%, 4% and 8% doping concentration (mass fraction) in emissive layer to fabricate OLED devices by spin-coating method, and the structure of OLED device comprises of ITO/PEDOT:PSS/PVK:PBD:Ir(cfpp)2(acac)/TPBi/LiF/Al. When the doping concentration was 8%, the maximum emission wavelength of OLED device appears at 524 nm with the maximum brightness of 3500 cd/m2. When the current density is 20 mA/cm2, the maximum current efficiency and power efficiency of the device are 2.0 cd/A and 0.6 lm/W, respectively, indicating that the prepared device shows the interesting characteristics of electroluminescence. The obtained results imply that it is a practical concept to design and synthesize the soluble organic electroluminescent materials for spin-coating procedure by introduction of the structural moiety of liquid crystal molecules.关键词：iridium(III) complex;liquid-crystal fragment;electrophosphorescence;OLED
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发布时间：2020-08-12 - 摘要：A series polyimides (PIs) were prepared by one-step method. These PIs were comprised of a functional diamine N,N-bis(4-aminophenyl)-4-(dodecylo-xy-biphenyl)-4'-amino-phenylether (C12-BAAPE), one of two commercially available diamines 2,2'-Bis(trifluoromethy-l)-4,4'-diaminobiphenyl (TFDB), 4,4'-Oxydianiline (ODA) and one of two dianhydride 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 4,4'-Oxydiphthalic anhydride (ODPA) in order to get different backbone structures. The structures and thermo properties of these PIs were characterized by NMR, FT-IR, DSC and TGA. Pretilt angles and alignment abilities were carried out by pretilt angle tester and polarization microscope. Solubility of PIs was tested by dissolving PIs in various organic solvents. DSC and TGA curves showed that PI-2 had higher glass transition temperature (Tg) and decomposition temperature (Td) than PI-1 and PI-3. Three PI films presented vertical alignment before mechanical rubbing and only PI-2 maintained it after rubbing process. Conformations of these PIs were simulated by Material Studio (MS). The vertical conformation existed in PI-2's backbones improved rubbing resistance and showed vertical alignment ability after rubbing.关键词：polyimide;backbone structure;LC alignment layer;vertical alignment;rubbing resistance
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发布时间：2020-08-12 - 摘要：Photosensitive polysulfone modified by UV curable reactive mesogeons has been jointly applied for in-plane switching liquid crystal device (IPS-LCD), and its high temperature electro-optic reliability and photoaligning stability have been further studied. It is found that modified photoaligning film shows enhanced electric-optic reliability and thermal stability (no easy axis drift under 65℃ with electric field stress of 20 h and no noticeable light leakage keeping 120℃ for 2 h) compared to pure photoalignment. It is also found that pure photoalignment before modifying shows anisotropic photo-crosslinking reaction of the side chain-chalcone moiety of polysulfone and photoreaction around 67.4% under polarized linear ultraviolet light using polarized ultraviolet absorption spectrum. Further studies with scanning electric microscopy demonstrate UV curable reactive mesogeons (RM) can be polymerized on pure photoalignment under UV irradiation, and the UV irradiation formed polymerized RM rods with averaged size around 0.4μm, which restricts mobility of the unphotocrosslined flexible groups in photoalignment, is responsible for strengthening the photoaligning surface.关键词：photosensitive poly(arylene ether);photoalignment;reactive mesogeons;alignment stability
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发布时间：2020-08-12 - 摘要：More and more application requires faster response speed for nematic liquid crystal materials at present. There is a direct relationship between response speed and birefringence. The fluorinated phenylethynyltolane compounds(Ⅳ)with high birefringence,low melting point were synthesized. Their structures were determined by IR,1H NMR,13C NMR. The liquid crystalline properties were tested by DSC and POM. It shows that these compounds synthesized exhibit low melting point and broad temperature range of nematic phase(with the range about 100℃). These compounds exhibit high birefringence(Δn >0.47) after being tested birefringence. These characters are particularly attractive for increasing response speed of liquid crystal materials and improve the optical properties of liquid crystal.关键词：fluorinated phenylethynyltolane compounds;synthesis;high birefringence;broad temperature range of nematic phase
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发布时间：2020-08-12 - 摘要：This research simulates the reflection spectrum of cholesteric liquid crystal by Berreman 4×4 matrix and Matlab program, and analyses the factors that affect the bandwidth of reflection spectrum, such as pitch number (thickness of liquid crystal), refractive index of substrate, birefringence, dispersion of refractive index, fixed pitch, pitch gradient, incident angle and so on. The result illustrates that in order to get an ideal Bragg reflection bandwidth, the thickness of the liquid crystal, the pitch number N, must reach N≥10; The substrate refractive index can impact the maximum reflection, which will be relatively low when the substrate refractive index ngis smaller than the common light reflection and the affection is more obvious as the ng becomes smaller when ng≥no,a pefect reflection can be attained.The dispersion reflection and big incident angle will make the bandwidth become narrow, while large birefringence Δn and pitch P lead to broader bandwidth, but the broadening effects is finite. The reflection bandwidth of the pitch gradient cholesteric liquid crystal was simulated theoretically by giving the function expression of pitch gradient, which makes sense for the experimental study of broadband reflection of cholesteric liquid crystal.关键词：cholesteric liquid crystal;Berreman 4×4 matrix;Bragg reflection;bandwidth;pitch gradient
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发布时间：2020-08-12
Material Physics & Chemistry
- 摘要：Final inspection critical dimension (FICD) is an important parameter to evaluate the performance of thin film transistor liquid crystal display (TFT-LCD) products. The method to obtain an accurate FICD data was studied in this paper. By a large number of experimental data and the scanning electron microscope (SEM) images,test conditions and methods were determined. Based on the above analysis,the center of illumination intensity which could provide stable measuring results was selected as the reference value,and the image was collected as golden sample simultaneously. By contrasting the above results and SEM results,the compensation value of the different layers between measured value and true value were obtained. Also the reliability was proved by data analysis of different sizes of products. As a result, calibration period of FICD measurement could be reduced greatly,and reliable test standard was provided for future products.关键词：final inspection critical dimension;measurement method;scanning electron microscope;compensation
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发布时间：2020-08-12 - 摘要：This paper demonstrated the top emitting white organic light emitting diodes (TEWOLED) with Cu top electrode, which achieved a brightness over 1000 cd/m2 at a operating voltage of 4 V with a power efficiency of 28.5 lm/W. With the modification of electron injection layer, Cu is able to work as a top cathode despite its high work function which fails to the lowest unoccupied molecular orbital (LUMO) of electron transporting layer, p type donation resolved the problem of Al work function unmatched with the highest occupied molecular orbital (HOMO) of the holes transporting layer. The angular property of the emission spectra was ameliorated by the introduction of TcTa capping layer. A prototype of SVGA TEWOLED is finally demonstrated. This study paves the way towards organic full-color micro display.关键词：top Emitting White Organic Light Emitting Diodes;Cu top electrode;SVGA white OLED microdisplay
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发布时间：2020-08-12 - 摘要：Bottom-gate structure TFT device technology on flexible PI substrate was discussed in the paper. Undercut shape of the double layer caused by the different dry etching rate was solved by the improvement of technics. The TFT device was based on IGZO as active layer, and Si3N4/SiO2 double layer structure was employed as gate insulator, undercut shape introduced thin film deposition break risk was effectively solved using two times of exposure compensation. The experimental results show that, the taper angle of double-layer structure after dry etching which was observed using SEM was suitable for following film deposition of TFT devices. The mobility of TFT on flexible PI substrate reaches 14.8 cm2/(V·s), threshold voltage of Vth is about 0.5 V, subthreshold swing (SS) is about 0.5 V/decade, and ratio of Ion/Ioff is upper 106. TFT device performance by this method is good, and meets the driving requirements of LCD, OLED or electronic paper.关键词：flexible;TFT;IGZO;mobility
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发布时间：2020-08-12 - 摘要：Active layers(a-Si) were etched by enhance cathode couple plasma(ECCP) and used as electronic channels in the thin film transistors.The uniformity of active layers and electrical characteristics were studied. The obtained samples were characterized by scanning electron microscopy (SEM) and electronic parameter measurement. The etching power, gas ratio and etching pressure played an important role in uniformity of active layers, which can cause the issue about TFT electrical characteristics. The uniformity of active layers can be improved by reduced the ratio about etching power ratio (source power/bias power) and reaction gas ratio (SF6/Cl2), meanwhile, reaction pressure was also reduced. Therefore, the uniformity of TFT electrical characteristics can also be improved.关键词：TFT;ECCP;active layers;a-Si films;uniformity
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发布时间：2020-08-12 - 摘要：Flexoelectric effect refers to the spontaneous polarization of LC molecules caused by splay/bend deformation while they are under the action of external electrical field. It would make the LC molecules show electric dipole moment which may produce DC offset in ADS (advanced super dimension switch) panels. The experiment result shows that flicker shift would happen because of flexoelectric effect when the ADS mode panel started to work. This paper investigated how the gray scale voltage and the gray scale voltage symmetry influenced the flicker shift of ADS panel based on the mechanism of flexoelectric effect and experiment result. The flicker shift includes two aspects, shift rate and degree, as well as the voltage of common electrode (Vcom) deviation. The result indicates that the flicker shift and Vcom deviation would intensify with the increase of gray scale voltage. And also the change of gray scale symmetry may enhance or relieve flicker shift and Vcom deviation caused by flexoelectric effect. In this way we may relieve the flicker shift and Vcom deviation in ADS panel so that the display performance could be improved.关键词：flexoelectric effect;flicker shift;gray scale voltage;gray scale voltage symmetry;Vcom voltage
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发布时间：2020-08-12
Device Physics & Device Technology
- 摘要：In TFT-LCD industry, PECVD equipment is mainly used for the vapor deposition in the process of Array TFT to produce non-metal film layer, which protects and switches metal circuit. In PECVD process, cavity design is complex and reaction conditions are harsh, the process will lead to bad products, so we need to do pre-maintenance on a regular basis. On the background of PECVD PM,we improved the method and emphatically introduced the cavity check-up leak tool design process because of the time-consuming of PM. We designed a domestic leak detection tool, and applied it into mass producing successfully. Final test results showed that pressure reached to 10 mT in 3 min and the leakage rate is 0.45 mT/min, which accord with the equipment standard.关键词：TFT-LCD;PECVD;cavity check up tools;independent design
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发布时间：2020-08-12 - 摘要：In order to quickly test the antenna beam alignment and Unicom IP address in installing the AIRMAX bridge debugging equipment, the bridge receiving signal strength, the signal-to-noise ratio, and other parameters in real time must be accurately measured. A low cost and simple bridge antenna instrument was designed using an ENC28J60 Ethernet controller to set up bridge Telnet connection to measure these parameters. Additionally, an ATMEGA328 processor was used to carry out information extraction and selection. The bridge parameter statuses were shown on an LCD1602 display. Experimental results show that this system's start time is less than 1 min, and it extracts and displays the Bridges RSSI and the NOISE value in every 0.5 s, satisfying the requirements of small, rapid and accurate debugging.关键词：bridge;antenna debugging;liquid-crystal display
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发布时间：2020-08-12 - 摘要：The fixed-time shot switching is usually used to monitor the public place, but this method has the untimely and some content-absence shortcomings. A new intelligent monitoring platform based on RFID technology is designed for overcoming these problems, which consists of S3C2440 processor, OV9650 camera and nRF24LE1 wireless chip components. The core algorithm is based on the pattern classification of the scenes, it can receive the wireless energy fluctuation, and the images will be monitored and shown on the screen where appears unusual situation. The experiments show that this new platform has overcome the shortcoming of fixed-time shot switching. In the medium scale video surveillance, the shot-losing ratio is improved greatly. This intelligent platform has realized non-leakage and real-time monitoring for the goods and personnel in the large area public places with the compact and low cost advantages. It can meet the needs of intelligent monitoring of public places.关键词：RFID;S3C2440;monitoring
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发布时间：2020-08-12 - 摘要：This paper proposes a new gate driver circuit integrated by IZO-thin film transistors (TFTs), which employs a new driving method called input block multiplex structure. One input block driving several output blocks is used in this method, which can reduce the number of TFTs and save the area of the circuit dramatically, satisfying the design of the high resolution and narrow bezel displays. The working time of the input block is n times as the output block, where the parameter 'n' is the quantity of output blocks driven by one input block. Therefore the frequency of the driving clock of the proposed circuit is 1/n of the traditional circuits, in which one input block is used to drive one output block. We have successfully fabricated 20 stages of the circuit. The structure is one input block driving two output blocks and the dimension is 730μm width and 164μm height, which can realize the narrow bezel easily. The experimental results show the circuit can work well and be suitable for 300 PPI displays of AMLCD or AMOLEDs.关键词：In-Zn-O thin-film transistor;integrated gate driver circuit;input block multiplex;output block
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发布时间：2020-08-12 - 摘要：Through the study of the large outdoor full color LED display screen, a control system of LED display screen was designed based on FPGA. The system was designed on the platform of the Altera DE1 development board. In the software development environment of QuartusⅡ, a hierarchical design was applied. A complete system module consists of a frequency divided clock module, a module for data acquisition and reorganization, and a scan driver module with the use of the Verilog HDL language. Simulation and test were also conducted for the final FPGA control system. Moreover, the design of a LED large screen was also verified by using the SPI communication protocol to send data to realize the graphic display of a 64×64 LED screen. The display control system method of this scheme met the demand of current LED area of the large screen display and image data high-speed processing, having the characteristics of high stability, flexible design etc.关键词：field programmable gate array;light emitting diode (LED);Verilog hardware description language;scan driver
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发布时间：2020-08-12
Driving & Controlling
- 摘要：A new method for skeleton extraction based on vector inner product was presented in order to improve the accuracy and connectivity. Euclidean distance transform is used to determine the nearest edge element for each pixel in a binary image. A vector from each pixel that stops at the nearest edge element is defined as edge vector. By comparing the inner product of edge vector within 8-neighborhood of the pixel, the number of significant changes in direction can be determined, and the candidate skeleton points can be selected according to it. Finally, a complete skeleton was generated by extending process based on regression analysis. Experimental results show that the algorithm can guarantee connectivity and integrity of the skeleton, and the average accuracy rate of location reached 92.27%. It also has advantages in reflecting the topological structures of objects and overcoming boundary disturbance. So, it is an effective skeleton extraction algorithm.关键词：skeleton extraction;distance transform;vector inner product
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发布时间：2020-08-12 - 摘要：In order to precisely measure the modulation transfer function of the space camera at any frequency before launching, the measuring method is elaborated and some experiments are carried out. On the basis of giving the schematic diagram of modulation transfer function measurement, the transfer process of a sinusoidal and a square wave at any frequency are investigated. Consequently, the modulation transfer function and the contrast transfer function are derived, based on which the conversion coefficient of them is obtained as π/4 at any frequency. Finally, an experiment is implemented and the modulation transfer functions at 1, 1/2 and 1/3 Nyquist frequency are measured based on a certain remote sensing camera. The experiment result indicates that the modulation transfer functions at 1, 1/2 and 1/3 Nyquist frequency of the remote sensing camera used are 0.21, 0.40 and 0.59 at lab condition. Moreover, the reduction between the optical system modulation transfer function calculated on account of test results and the design value is near 1, which proves our derivation in this paper.关键词：remote sensing;modulation transfer function;measurement;TDI CCD
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发布时间：2020-08-12 - 摘要：The traditional luminance meter takes too much time to detect the backlight luminance so that it is hard to take bulk-production in the engineering practice. To solve these problems, the paper puts forward an evaluation method of backlight luminance uniformity based on ε-support vector regression. A backlight luminance uniformity testing platform is designed. First of all, a CCD image sensor is used in a single shot to get a digital image of several backlights, and the image is corrected. Secondly uses ε-support vector regression (ε-SVR) in the condition of nonlinear to test the luminance values of check points in backlights, and forecast the real luminance values of backlights. At last, it is compared with the testing standard to judge whether the backlights are qualified. The results show that the fusion of parameters can be tested in the constructed support vector regression. And their accuracy shows good similarity. RMSE of the best prediction is 43.28, BR is 1.21%. The error between the predicted results and these results of the measurements of the traditional luminance meter is much less, and it is easy to operate. The evaluation results of luminance meter are accorded with the method of the objective evaluation of the backlight luminance uniformity.关键词：optical detection;backlight;CCD;ε-SVR
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发布时间：2020-08-12 - 摘要：A new type of coaxial ultra short focal projector was designed in order to reduce the alignment difficulty, reduce the difficulty of system design and shorten the total length. Firstly, by analyzing the relationship between the system's total length and the aberration, the necessity of ensuring a long system's total length is proved. Then, through hollowing the central portion of an aspherical mirror and using a plane or spherical mirror to deflecting the optical path, a new design method for ultra short focal length projector is presented. It solves the blocking problem existing in the coaxial catadioptric optical system and improves the space utilization rate by ensuring a long total optical length and shortening the overall machinery length. Finally, the system's screen size is 100 in and the total length of 215 mm. The focal length is 1.66 mm and the object NA is 0.2 with 0.17 throw ratio. The MTFs of every field are over 0.5 at the Nyquist Frequency. All of the indexes meet the demand of the projective system. Meanwhile, in the case of the same number of lenses, the system's performance is better than the conventional projector.关键词：optical design;projection system;catadioptric system;ultra short focal
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发布时间：2020-08-12 - 摘要：A kind of panel display module source using RGB LED as backlight is introduced in this paper. Frequency diming method is used to adjust backlight brightness. The final standard white light is gained by RGB diming pulse high level mixing color method. And besides, RGB diming pulse high level timing is tuned according to data from color sensor. Using the method, backlight brightness,color varies and coordinates drifts caused by temperature varies can be effectively improved.关键词：backlight of LED;mixing colors;diming
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发布时间：2020-08-12 - 摘要：Auto-Stereoscopic with improved spatial and sequential hybrid control (SSHC) is a new type of auto-stereoscopic display technology which retains full resolution and low crosstalk ratio. It eliminates the temporal crosstalk caused by the non-synchronization between the screen and the backlight module, which is one of the key issues of auto-stereoscopic display with SSHC. The paper explains principles of auto-stereoscopic display with SSHC and dynamic backlight system. Two different refreshing strategies of backlight module are introduced, which are the scanning type and the vertical type. Comparison on the influences on the luminance and crosstalk ratio of the display system for both strategies is mainly discussed. The optimal settings for backlight module are achieved through experimental results. Experimental results show that the crosstalk ratio of the display system can be suppressed as low as 2.64% with the optimal settings, which proves that the dynamic backlight control technique can effectively lowers temporal crosstalk.关键词：auto-stereoscopic display;dynamic backlight;temporal crosstalk
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发布时间：2020-08-12
Imaging Technology & Image Processing
- 摘要：Method for automatic optical inspection system with periodic comparison and logic operation can obtain defect point information. Because of the existence of minimal cycle comparison of Pitch decimal, we cannot get the correct comparison. The use of two points formed one line, we can construct a linear equation to simulate the original breakpoints into continuous points. Just then, whether the comparative distance is an integer, the corresponding effect is found in the gray value. Using this method to improve the accuracy of anomaly check, the adverse effect is avoided on the yield, quality and cost of the product, which has the vital significance.关键词：auto optical inspection;color filter;error detection;equation
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发布时间：2020-08-12 - 摘要：In order to set up a standard for evaluating key properties of autostereoscopic display, crosstalk ratio, luminance, contrast, color temperature and color gamut are measured according to different displaying principles. As the measurement result shows, in terms of crosstalk ratio, directional-backlight autostereoscopic display is superior to lenticular-lens (80.91%) and barrier (3.3%) autostereoscopic display with the lowest crosstalk ratio of 2.64%. Besides, directional-backlight autostereoscopic display outclasses the other two kinds of displays in luminance, color gamut and color temperature. However, in the aspect of contrast, lenticular-lens autostereoscopic display surpasses the other two types of displays with the best value.关键词：autostereoscopic display;evaluation;crosstalk ratio
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发布时间：2020-08-12
Measurement Technology
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