最新刊期
期 2 ， 2013
- 摘要：Chiral dopants based on optically active (+)-2-methylbutan-1-ol were prepared. Two kinds of induced chiral nematic liquid crystal (N*-LC) were achieved by mixing the chiral dopants in 4-n-alkyl-4'-cyanobiphenyl (CBS) host nematic liquid crystal. The helical pitches of the N*-LC were measured and the regularities of change were analyzed. The results showed that the steric hindrance in the chiral region contributed to the helical twisting power (β) of the N* phase. The substitution between the two chiral center had a strongly effect on β and the temperature dependence of the helical pitch (dp/dt).关键词：chiral dopant;helical twisting power;helical pitch;liquid crystals
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发布时间：2020-08-12 - 摘要：Molecular self-assembled monolayer (SAM) technique is used for ferroelectric liquid crystal (FLC) alignment, and with using conventional rubbing technique, hybrid-aligned FLC cell is fabricated. Without applying electric field during phase transition of FLC, mono-domain alignment of FLC device is obtained. Experimental results show that contrast ratio increases with the polarity of SAM terminal group. Based on molecular simulation and analysis of alignment principle, it is concluded the directions of Ps near the SAM and the rubbed substrates are consistent under Ps action between FLC molecules and SAM terminal groups. Via molecular interaction within surface-bulk transition region, the molecules in FLC cell could form mono-domain alignment with no defect.关键词：ferroelectric liquid crystal;self-assembled monolayer;hybrid;mono-domain
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发布时间：2020-08-12 - 摘要：Graphite powder as the raw material was directly sonicated in organic solvents by the liquid-phase exfoliation method, to produce high quality graphene dispersion through a high-speed centrifugation. The spray-coating method was used to prepare transparent and conductive graphene films based on flexible substrates (PET). The influence of different organic solvents and substrate treatments on the surface morphology and photoelectric properties of graphene films was studied by SEM and four-point probe tester characterization methods. The results show that graphene films are less structural defects and don't introduce other functional groups by using DMF as the dispersant. The substrate processed with silver metal grid can effectively reduce sheet resistance of the film, and the sheet resistance is reduced to 172 Ω/□ when the transmittance is 81% (λ=550 nm).This new structure of graphene/silver metal grid flexible transparent conductive film is expected to replace the market mainstream ITO film.关键词：graphene;liquid-phase exfoliation;flexible substrate;silver metal grid
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发布时间：2020-08-12 - 摘要：The effective dielectric constant of liquid crystal filled in this cell will change under an external applied voltage, which can result in the variation of the capacitance in liquid crystal cell. Because liquid crystal cell itself may be seen as a capacitor, its capacitance is tunable with different external applied voltages. Based on liquid crystal elasticity theory and variational principles, the analytical expressions of the capacitance in strong anchoring parallel aligned nematic (PAN) and hybrid aligned nematic (HAN) liquid crystal cell are deduced theoretically. The capacitance-voltage curves of these two cells are also obtained by numerical simulation. From the data analysis, there exist some differences for the capacitance characteristics between the two types of cells, especially in the case of low voltage. To obtain the wide range tunable capacitance, the liquid crystal material with the smaller elastic constant and the larger dielectric anisotropic constant should be chose for PAN cell; however, for HAN cell, the situation is reversed. When a high voltage is applied to the liquid crystal cell, the choice of liquid crystal material for two types of cells is consistent.关键词：liquid crystal tunable capacitor;effective dielectric constant;parallel aligned nematic;hybrid aligned nematic
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发布时间：2020-08-12 - 摘要：Diazafluorene derivatives and its complexes with metals are widely explored in the fields of chemistry, organic optoelectronics, biochemistry, and etc. The basic chemical structure, chemical properties, and application in the organic light-emitting devices of diazafluorene derivatives and complexes are reviewed. The problems in the chemical synthesis and application in the devices, as well as the possible solutions, are also discussed.关键词：diazafluorene;organic material;metal complex;optoelectronic device;electroluminescence
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发布时间：2020-08-12 - 摘要：Several organic electroluminescent devices with different cycle of quantum well structure and different barrier thickness have been demonstrated. The quantum well structures were composed by tris-(8-hydroxyquinoline) aluminum (Alq3) and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP). The Alq3 layer is the potential well of electrons and BCP layer is the potential barrier of electrons. The twice well structure device exhibits the highest current efficiency of 3.46 cd/A, which is about 1.6 times of the conventional three-layers organic light emitting devices. The current efficiency improved owing to carrier confinement and higher exciton formation probability in the well layer (light-emitting layer) when the quantum well period increasing, then the current efficiency would enhanced. But when the quantum well period is too large, the current efficiency will decreased. The devices with different barrier thickness have also been studied in our research, the influence of barrier thickness on current efficiency have been compared. Results illustrated that proper well number and barrier layer thickness can improve the current efficiency of organic light emitting devices.关键词：organic quantum well structure;electroluminescence;brightness;current efficiency
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发布时间：2020-08-12 - 摘要：The Acrylate resin layer has lower dielectric constant(ε≈3.5),better optical transparency, and can be spin-coated as a flat surface film easily. By using resin as passivation layer in the array process, the vertical gap is increased between the Common ITO and bus line and plannar the devices. This reduces unwanted capacitive coupling and enables the pixel electrode to be extended over the gate and data lines, thus increasing aperture area, specifi-cally decreases power. In this work, there were some problems between the resin passivation layer and pixel ITO, such as Mo attack, missing ITO and so on. After optimizing the process of ITO Etching, photosensitive resin and non-photosensitive resin perfectly match with ITO etchant and Resin Coating, the resin passivation layer is sucessfully applied to the TFT-LCD.关键词：resin material;ITO etching;ITO etchant;Coating process
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发布时间：2020-08-12
Material Physics & Chemistry
- 摘要：A micro-lithography system based on digital micro-mirror device is utilized in liquid crystal (LC) alignments. The projected images on SD1 guide the SDI molecular orientations of the command layer, and further determine the directors of LC. Both complex pattern fabrication and arbitrary polarization control could be accomplished on this system with resolution up to 5 μm. Pattern transforming among different bar codes and subarea controlling of random gray scale have been demonstrated by means of the optical rewritability of SD1. These LC devices are switchable and tunable under applied fields. The dynamic LC photo-patterning technique may be widely used in information display and identification, tunable photonic devices, etc.关键词：DMD;liquid crystal;photoalignment;2D barcode;gray scale
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发布时间：2020-08-12 - 摘要：Nowadays, much attention had been paid to the investigation of Touch Mura, which affects the performance of products seriously. It has been observed frequently during the manufacturing process of TFT-LCD products. In this paper, several important impact factors to the Touch Mura were systematically studied, including the liquid-crystal quantity, the designing of sub PS, the designing of height difference between main PS and sub PS, and the total pitch (one of the process parameters). The experiment results demonstrated that the increment of liquid-crystal quantity can compensate the touch shift; thereby the decrease of the defect rates in Touch Mura will be lead to a certain extent. The "Z" design of sub PS can ease the Touch Mura effectively due to the blocking effect. Besides, it was also found that the more height difference between main PS and sub PS, the smaller Touch Mura margin is; meanwhile, if it set the parameter of total pitch close to the design values, the Touch Mura will occur in a very little chance. In conclusion, in order to reduce the risk of Touch Mura, it can obey the following ways in the new frame, including the proper using liquid-crystal quantity, the optimum designing of sub-PS, and the metering the height difference between the main and sub PS. In addition, the controlling of total pitch is also of great importance in manufacturing process.关键词：touch Mura;liquid crystal amount;post spacer;total pitch
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发布时间：2020-08-12 - 摘要：This paper analyzed the contact resistance between inkjet-printed silver source/drain (S/D) electrodes and organic semiconductor layer of Organic Thin-film Transistors(OTFTs) using transmission line method(TLM). Spin-coated PVP thin-film and Tips-pentacene thin-film were used as gate dielectric layer and semiconductor layer, respectively. S/D electrodes with four different channel lengths of 200,250,300 μm and 400 μm were inkjet-printed,and the annealed time of different semiconductor layers was 2 h,6 h and 10 h,respectively. The extracted contact resistances were 8 MΩ,4.5 MΩ and 3 MΩ for OTFTs with three different kinds of annealed time, respectively. Lower contact resistance for OTFTs with annealed time of 10 h can be explained by the fact that longtime annealing can reduce the impurity in the semiconductor layer and lower the contact barrier between electrodes and semiconductor layer.关键词：transmission line method;organic thin-film transistor;contact resistance;inkjet-printing
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发布时间：2020-08-12 - 摘要：In order to study relationship between Flicker and Ioff-p in TFT-LCD, a large amount work had been made. Flicker of obverse and reverse of 3 panels were observed by CA310. The relationship between Flicker and BLU brightness were researched. Brightness of obverse and reverse of 3 panels were also researched by photo sensor amplifier in Flicker pattern. I-V curve was measured by semiconductor parameter equipment. All results show that Ioff-p was too large to pixel voltage couldn't hold, then brightness of odd frame and even frame was different, and Flicker became serious.关键词：TFT-LCD;flicker;Ioff-p;brightness;pixel voltage
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发布时间：2020-08-12 - 摘要：A new film stripped technology from color filter substrate with photo space layer was presented. Two steps were used. The first step was that the photo space was easily stripped by stripper used for 260 s. The second step was that etcher and stripper were used for 650 s in this process. The result was that the ITO & Color & light blocking layers could be stripped completely. Finally, color filter substrate changed to the bare glass back that could be re-used.关键词：strip technology;photo space layer;indium tin oxide film;etcher;stripper
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发布时间：2020-08-12 - 摘要：Improved 4-Mask process was developed in order to reduce manufacturing process.This process has several issues.If the delay time between Active Etch and 2SD Wet Etch was too long(≥5.9 h),there will be Al corrosion in the channel by Cl2 which is used by Active Etch. However, it brings a matter to a successfully settlement and meets with good results about Al corrosion prevention with adding SF6/O2 in the After-Treatment of Active Etch. Moreover, it brings successfully results to be applied to improved 4-Mask process.关键词：active layer;corrosion
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发布时间：2020-08-12 - 摘要：Due to advantages of simple, beautiful and large visual area, slim border display panel becomes main development trend of high quality display panel. According to the related information from FPD, this paper introduced development trend of slim border panel for mobile display. At the same time, it researched the development of panel fan-out design, sealant curing and LC dispensing process and equipment, which has strong support for slim border.关键词：mobile display;slim border;sealant dispensing;LC dispensing
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发布时间：2020-08-12 - 摘要：Normal naked 3D display have some defects,such as fixed viewing point, narrow viewing angle. In order to enhance the 3D performance, a 3D display system base on head tracking is introduced. In this system, a camera detects the position of observer's face, and a LC barrier moves the 3D viewing point toward the face simultaneously by changing its transmissive area. Thus the observer can receive good 3D images freely within the visual field of the camera. Because there is no meteyard for this wide viewing angle 3D display, this paper puts forward a test method.The experiment result proved the method is viable.关键词：head tracking;naked 3D display;LC barrier
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发布时间：2020-08-12
Device Physics & Device Technology
- 摘要：BT.656 is a wildly used digital video Stream. However, display devices, such as LCD monitor, LED display area array, as well as part of the micro-projection devices, can only be displayed directly to the video signal of the RGB color space. The conversion from BT.656 to RGB Video Stream consists processing of de-interleave, interlaced to progressive, color space conversion. BT.656 protocol was introduced, and platform based on field programmable gate array implementation of the progressive video of the 24-bit RGB color space was expounded. System on Chip which video information was stored by utilizing multi-port SDRAM timing controller, and then in turn to complete the follow-up processing was designed by Verilog Hardware Hardware Description Language. The system was verified on an independent developed Micro-Projection system, 24-bit true color of resolution up to 852×480 at 30 frames per second in real-time processing and transmission was achieved. Then, the system is flexible, reliable, of short development cycle and cost-saving in hardware (merely accounted for 1 783 logic elements), which avoids cumbersome floating-point operations in color space conversion.关键词：video processing;field programmable gate array;micro-projector;ADV7181;verilog hardware hardware description language
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发布时间：2020-08-12 - 摘要：Currently, intelligent transportation systems (ITS) proposed a new demand that the VMS should have the ability to choose the most simple and effective means of communication according to the different environments as well as higher demands in the stability and reliability of the communication. In view of this situation, combined with the embedded technology and network communication technology, this paper proposed a communication system based on embedded highway VMS. The system uses MC703CDMA EV-DO 3G module and DM9000CIEP network chip, combined with the powerful networking capabilities of Linux operating system, has the ability of 3G wireless network, 10/100M adaptive Ethernet communication and RS485 serial interface communication. The system has high effectiveness and stability in communication, at the same time it can selected different communication methods according to the specific environment.关键词：multi-communication methods;network communication;serial communication;3G communication;Linux
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发布时间：2020-08-12 - 摘要：In order to satisfy the requirements of more and more complex man-machine interface,one touched display GUI system based on SOPC technique is designed by using FPGA device. The LCD screen and touchpad is driven by FPGA device in this system. The GUI graphic interface module is run by build-in SOPC soft core processor. The method only brings the interface image needed into the FLASH memory. And next using a serial port connects to the host MCU, which has the advantages of simple development, elegant interface and excellent applicability, comparing with disadvantages traditional method with long-time design and poor universality.关键词：FPGA;GUI;touch screen
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发布时间：2020-08-12 - 摘要：Compared with CRT projection and LCD, displaying system based on digital micromirror device (DMD) has its own advantage. The performance, gray-level modulation and color controlling method of the video displaying system based on DMD are analyzed in detail. At first, the principle of DLP Discovery4100 DMD module was given. Also, the spatial and temporal gray-level modulation was introduced. Considering the feature of those two methods, one color controlling method of chromatic video based on temporal gray-level modulation was proposed. In this method, frame period was equally divided to be the R, G, B section. In each of the R, G, B section, status of the micromirror in the DMD was controlled according to the gray-level of corresponding color. Considering the DLP Discovery4100 DMD module, the relationship between gray-level, video frame frequency and DMD type was given. Analyzing result shows that, when same gray-level is selected, the maximal frame frequency of three DMD chromatic video displaying system equals to that of gray video displaying system, while the maximal frame frequency of single and double DMD chromatic video displaying system is just 1/2 and 1/3 of that level. Analyzing result could provide academic basis for designing of video displaying system.关键词：digital micromirror device;video display;gray-level modulation;color controlling
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发布时间：2020-08-12 - 摘要：At present, the Embedded Linux operating system is rapidly developed and has wide application in handheld devices and mobile equipment.Therefore, possessing a practical friendly graphical user interface is particularly important.This article illustrates the transplantation of Qt/Embedded to Embedded ARM9 in detailed through the mode of crossing compile source repository and application,solves the problem of the cross-platform application not running,and expounds application combined with the development process.关键词：embedded Linux;embedded GUI;QT/embedded;transplantation
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发布时间：2020-08-12
Driving & Controlling
- 摘要：In order to speed up video encoding, a new fast algorithm is proposed, on P-frame mode decision which has high complexity in H.264/AVC. In the proposed algorithm, the check range of candidate inter modes are reduced gradually through the following two steps: the monotonicity check of Jmode and the selection of horizontal or vertical orientation based on sub-blocks' motion vector (MV). Meanwhile, an intra mode checking method based on the best inter mode is proposed, which check intra modes selectively. Thus, it is avoided effectively that checking unnecessary modes. The experiment results show that, compared with exhaustive mode decision algorithm in the JM, the proposed algorithm reduced the encoding time about by 63.80% on average, while brought negligible performance degradation.关键词：video coding;H.264/AVC;P-frame mode decision;monotonicity of Jmode;sub-block's MV
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发布时间：2020-08-12 - 摘要：For the human object recognition under occlusion,the human characteristics description are vulnerably effected under occlusion, but the head and shoulder of the human body are less susceptible to the characteristics of the block, put forward a new method based on the human head and shoulder mixed contour features for human object recognition under occlusion. First, using background subtraction method to separate the human body from the complex background, and then using a priori knowledge of the human body to extract the head and shoulder parts, then the contour moment invariant and Harris angular points are extracted and fused into a mixed feature, finally put the mixed feature into BP neural network to recognize. The experiments show that the method has better robustness and higher recognition rate.关键词：human body recognition under occlusion;moment invariants;Harris angular points;BP neural network
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发布时间：2020-08-12 - 摘要：Improve on the matrix filling rule of the integer DCT transform radix, a new type of integer transform radix was obtained, called variety integer DCT transform radix. Filtering the numerous of variety integer DCT transform radix, some optimum radix was obtained, and was applied to MPEG4 coding and decoding experiment, the analysis results of test data show that the normalized matrix of variety integer DCT transform radix have similar de-correlation characteristic with the original DCT matrix, and can replace functions of the integer DCT transform radix in image and video coding. Because variety integer DCT transform can be implemented by rapid butterfly algorithm completely, and can be implemented by hardware easily, applying to image and video coding, can reduce the complexity of coder and decoder greatly.关键词：integer DCT transform;de-correlation;rapid algorithm;image coding;implemented by hardware
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发布时间：2020-08-12 - 摘要：In order to solve the problem that the image data for the remote sensing aerospace camera is hard to store parallelly,which frequency is over 100 MHz, a multi-channel high-speed short blanking period CCD image data storage method is put forward. Firstly multi-channel image data are parallelly stored to SDRAM array, and then read out image data from SDRAM array and finally stored to computer's hard disk channel by channel via the frame grabber; for the problem of SDRAM fixed time refresh,the input image data's width is changed in order to reduce the SDRAM clock frequency; serial-parallel conversion and parallel-serial conversion operation combined with asynchronous FIFO are used as interface of diffe-rent clock domains,in order to solve the high speed image data non-integer times of the data width conversion, the formulas which are minimum depth of asynchronous FIFO and lowest operating frequency of the SDRAM are given. Research and application results show that the design based on FPGA as the data processing and controlling center meets the application requirements,the total parallelly writing data rate is up to 4.13 Gbit/s.关键词：multi-channel;high-speed;short blanking period;parallel storaging;bit width conversion
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发布时间：2020-08-12 - 摘要：In order to effectively clear away the speckle in SAR images, while preserving the SAR images edge detail,the application of BF (bilateral filtering) is extended to SAR images despeckling.The despeckling evaluation indexes, including the equivalent number of looks and the edge preserve index, are used to estimate the parameters. After BF with estimated parameters imposed on a normalized SAR image, the filtering result can achieve both despeckling and edge preservation simultaneously. Experimental results show that the visual quality and evaluation indexes of the proposed algorithm outperforms that of the classical Lee filtering alogrithm.关键词：despeckling;bilateral filtering;edge preserve;ENL;EPI
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发布时间：2020-08-12 - 摘要：A new method for accurate determination of the location and shape of metallic object in X-ray computed tomography by a binary image reconstruction technique is proposed. The binary image reconstruction technique used here is based on tangent back-projection(TBP). The proposed method firstly uses geometry of Fan-Beam CT scan to obtain simulated raw sinogram. Next, based on region growing image segmentation, the metal region sinogram is segmented from simulated raw sinogram. The final binary image is reconstructed by TBP. A computer simulation experiment demonstrated the proposed method can accurately determinate the location and shape of metallic object in digital phantom.关键词：Tangent back-projection;simulated raw sinogram;region growing image segmentation;location of the metallic object
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发布时间：2020-08-12
Imaging Technology & Image Processing
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