最新刊期
期 2 ， 2016
- 摘要：Polymer dispersed liquid crystal (PDLC) is a commercially available technique which is already utilized to scattering mode light switching and also developed in electrically privacy-switching window. However, there is still essential to be discussed that the ultraviolet (UV) stability and tolerability in organic liquid crystal (LC) materials and polymer structure for outdoor applications, especially the rarely discussed polymer structure. The electro-optical (E-O) effects of UV light-irradiated PDLC in different curing condition are compared in this work. The understanding of UV stability in polymer structure and the improved methods are expected. The precursor is prepared by the high UV stability host LC and optical adhesive (OA). In order to realize the effect between different polymer structure morphology, the proportion of the optical adhesive and the curing intensity are discussed in this work. The results revealed that the threshold voltage only slightly rose but the response time dramatically increased. For example, the threshold voltage slightly rose from 15.57 V to 18.18 V, the field off time dramatically increased from 195.12 ms to 925.26 ms under 35% OA concentration and 2 mW/cm2 curing intensity. In addition, it is observed that the response time after UV irradiation is more sensitive to the voltage duration time than before. This phenomenon can be suppressed by controlling the curing intensity and OA concentration. This work demonstrated the variation of E-O effect in different type of PDLC after irradiating UV light. The influence from polymer structure is realized.关键词：polymer dispersed liquid crystal;ultraviolet light stability;threshold voltage;response time
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发布时间：2020-08-12
Invited Paper
- 摘要：The azo-dye-doped liquid crystals (ADDLCs) have strong third-order optical nonlinearity, which arises from multiple nonlinear mechanisms, including photo-induced thermal effect and isomerization effect, etc. In this paper, in order to obtain the value of third-order optical nonlinearity in ADDLCs, we use a method of nonlinear interferometry to measure the change of refractive index at the wavelength 632.8 nm, deriving from intensity's change. A temperature equivalent method is proposed to quantitatively measure the contribution of thermal effect to the third-order optical nonlinearity, which simulates equivalent thermal effect through heating the ADDLC sample and producing the same temperature change as the irradiation light induces. Through this method, the thermal effect can be distinguished from multiple nonlinear effects. By measuring the change of refractive index and the corresponding temperature and intensity changes, we have obtained the value of third-order optical nonlinearity originating from thermal effect. Besides, a double-beam interferometry is used to improve the accuracy of measurement and eliminate the error from environmental shock, which increases the accuracy substantially. The measurement results show that, at the wavelength 632.8 nm, the third-order optical nonlinear coefficient n2of DR1-doped LC is 0.268 cm2/W, to which the contribution of thermal effect is 0.091 cm2/W.关键词：third-order optical nonlinearity;azo-dye-doped liquid crystal;thermal effect;temperature equivalent method;double-beam interferometry
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发布时间：2020-08-12 - 摘要：At present, the TFT-LCD industry is maturing. The panel enterprises continue to improve competitiveness of their products; high resolution, high color gamut, narrow bezel and high contrast ratio and so on. This paper expounds how the design of array substrate matches the alignment film diffusion. It is said that the via hole in the array substrate could block the alignment film diffusion uniform. With the upgrade of the coating method of alignment film and array substrate design,it has been improved.关键词：polyimide;alignment film;ink-jet printing;via hole
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发布时间：2020-08-12 - 摘要：A novel Side-Chain Liquid-Crystalline Polysiloxanes containing two Mesomorphic monomer with Cyclohexane (PAB) was synthesized by graft polymerization, using (trans, trans)-4-propyl-4'-vinyl-bicyclohexane(MA) and (trans, trans)-4-propyl-4'-butenyl-bicyclohexane(MB)with Cyclohexane groups, and the production rate is 80.3%. The molecular structure of PAB was confirmed by means of Fourier transform infrared spectroscopy and Hydrogen-nuclear magnetic resonance spectra. Liquid crystal phase and liquid crystal behavior of PAB were analyzed by polarizing optical microscopy(POM) and X-ray diffraction(XRD), illustrating the cholesteric oily striated texture and platelet texture during increasing and decreasing temperature, and different texture character resulting from order of molecular chain. Thermal properties of PAB were analyzed by differential scanning calorimetry(DSC) and thermal gravimetric analyzer (TGA), confirming the Mesomorphic region of 28.68 K and the 5% TG temperature(Td(5wt%)) of 405.25 ℃, which are higer than that of MA and MB.关键词：cyclohexane liquid crystal;side-chain liquid-crystalline polysiloxanes;cholesteric platelet texture;mesomorphic region
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发布时间：2020-08-12 - 摘要：Owing to their excellent electrical, thermal and mechanical properties, chemical stability and unique one-dimensional nanostructure, carbon nanotubes (CNTs) have been ideal functional materials for application in micro and nano electronic devices. Comparing to traditional electronic devices, CNT-based electronic devices have unique properties. In this paper, recent progress on research of producing and improving CNT-based field emitters, transistors and sensors is reviewed. After assembling and processing by certain methods, CNT-based field emitters possess low threshold voltage, high emission current, and stabilized emission current. CNT-based transistors have high mobility, large transconductance and on/off switching ratio. The sensitivity of various CNT-based sensors has been improved.关键词：carbon nanotube;application;field emitter;transistor;sensor
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发布时间：2020-08-12 - 摘要：The growth characteristics of phthalocyanine thin films were investigated by the method of heterogeneous induction due to planar electron conjugated bond structure of phthalocyanine thin film. Copper phthalocyanine organic thin film transistors were fabricated, which consist of high-doped silicon as the gate, the oxide silicon as the insulating layer, and the growth of α-tetrathiophene or para-hexaphenyl thin film as heterogeneous layer. The growth characteristics of the films were studied by atomic force microscopy. And the effect of two kinds of inducting layers on the properties of thin film transistors was contrastively investigated. The experimental results showed that copper phthalocyanine thin films grown on α-tetrathiophene were lamella morphology, and the copper phthalocyanine thin films grown on para-hexaphenyl were needle morphology, and they were different from rod shape of monolayer copper phthalocyanine. At the same time, the electric properties of two transistors were improved by the growth of copper phthalocyanine on α-tetrathiophene or para-hexaphenyl films, which were one or two orders of magnitude higher than the monolayer copper phthalocyanine. It was confirmed that the α-tetrathiophene and para-hexaphenyl films had induction effect on copper phthalocyanine thin films, and organic thin film transistor with high performance could be obtained.关键词：α-tetrathiophene;para-hexaphenyl;copper phthalocyanine;organic thin film transistor;induced effect
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发布时间：2020-08-12 - 摘要：In order to improve bright dot repair success ratio, a model of BM diffusion method was established and improved in experiment. Actors that effect success ratio were analyzed by a serial of experiments, and these actors included laser pumping type, laser wavelength, sport size, repair speed, color filter design, recipe type, etc. First by analyzing FIB image, a repair model was established. Then, repair success ratio in different conditions were calculated. Based on above analysis, success ratio of a hard-repair product was improved. Experimental results indicated that the model of repair process included three steps: Generating Gap (about 1.5 μm thick), making BM into Granule and Gap Filling. By comparing success ratio, following conclusions were obtained: Laser Diode pumping laser was better than flash lamp, B wavelength laser was better than A, Spot size of 1/2 sub-pixel and repair speed between 100~200 μm/s reached better success ratio in Gap repair and product with overcoat and high BM ratio gained higher repair success ratio. Based on repair model and effect actor analysis, success ratio of the hard-repair product increased from 40% to more than 90%.关键词：BM diffusion;repair success ratio;laser;effect actors;color filter
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发布时间：2020-08-12
Material and Device
- 摘要：At present, a lot of deep space exploration use CCD as high resolution camera sensor. Compared with CCD image sensor, area array CMOS has advantages of simple drive, low power consumption, and high radiation tolerance. CMOS is currently the trend of the development of deep space remote sensing detection. Therefore, a large area array CMOS high resolution camera was designed and implemented, using CMOS image sensor CMV20000 produced by CMOSIS company, the image resolution is 5 120×3 840. The overall structure of the FPGA as the core of the electronics system was described. Combined with CMV20000 operation mode and sequential circuits, the high speed transmission of high resolution images and data correction were realized. Experimental results show that the design of camera system is reasonable, the problem that the CMV20000 data cannot be aligned was solved. The operation of the system is stable and reliable, the high quality images can be acquired after installing the optical system.关键词：large area array CMOS;high resolution;FPGA;high speed data correction
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发布时间：2020-08-12
Driving and Controlling
- 摘要：Algorithms that have better performance also need more arithmetic operations. As a result, they will consume more hardware sources. In this paper, a new algorithm which has low complexity is proposed. Bayer pattern image is pre-interpolated by using Hamilton-Adam (H-A) algorithm firstly. Then the color-difference channel (CDC) and a direction factor (DF) in a 5×5 template are evaluated. Green channel is updated by using CDC and DF. R and B channel is evaluated via interpolated G channel. Simulation by Kodak test images shows that the algorithm has high PSNR. Experimental results also show that the algorithm not only maintains the sharp edges but also suppresses the speckle phenomenon which will be induced by VCD and MSG algorithm. Moreover, the algorithm just needs 56 arithmetic operations per pixel and can be accomplished via FPGA while MUL (multiplication) and DIV (division) are not needed. As a result, the proposed algorithm eases the burden of IP core in FPGA accomplishment and it's easy to be accomplished. The algorithm satisfies the needs for our camera.关键词：demosaicing;low complexity;Bayer pattern;color-difference channel
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发布时间：2020-08-12 - 摘要：The speech time-domain waveform and spectrogram analysis results displayed simultaneously on the VGA screen are required in the research and design of spectrogram based on FPGA, by general method, only parts of the waveforms can be displayed in the limited VGA display area, and failed to display complete speech signal waveform. To solve this problem, a method suitable to display VGA speech signal waveform based on FPGA implementation is presented in this paper. By analyzing the speech signal wave characteristic and the problems of waveform zooming in/out in the waveform display, we proposed the solution of linear interpolation and keep-extremum method, and discussed the FPGA implementation structure of the two methods in detail. Experiments show that speech signal can be displayed properly by the method.关键词：field programmable gate array;speech signal;waveform zoom;waveform display method;video graphics array
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发布时间：2020-08-12 - 摘要：Its difficult for traditional speckle suppression methods such as local single pixel filters and transform -domain filters to obtain good suppression effects in laser active imaging. Meanwhile, these methods would broaden edges, so as to damage the information of the image. In view of the excellent suppression performance of non-local filters for additive noise, three representative nonlocal filtering methods are introduced into laser active imaging. An active imaging system was built up to compare the performance of these three methods in speckle noise suppression using a diode-pumped solid-state pulsed laser. Experimental results indicated that homomorphic FM-PatchGP can not only suppress speckle noise effectively, but also preserve edge information while satisfies the real-time requirement, which leads to a good application prospect in laser active lighting systems.关键词：laser active imaging;speckle noise;non-local filters;homomorphic transform
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发布时间：2020-08-12 - 摘要：To achieve spectral characterization of LCD, a spectral characterization model based on GA-BP neural network and PCA was proposed in this paper. Firstly, color space of monitor was divided into subspaces and principal component analysis (PCA) was used to dimensionality reduction of the spectrum reflectance. Then genetic algorithm (GA) was adopted for optimizing the weight threshold of BP neural network in subspaces. A BP neural network was established to describe the transformation model of driver value and spectral reflectance. Lastly, the spectral characteristics model of LCD was realized. Experimental results show that model parameter optimization in the subspace is beneficial to the improvement of the model of overall after subspace division. The extremum problem of BP neural network can be improved by GA effectively.PCA can improve the operating efficiency of algorithm under the circumstances of maintaining accuracy. This implies that it is a high-precision display characteristic model.关键词：BP neural network;genetic algorithm;spectral characterization;LCD;principal component analysis
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发布时间：2020-08-12 - 摘要：Space camera ground detection system before being put into service must be carried out self-test function testing strictly. In order to solve the problem of waste of time and resources when testing with the massive CCD camera system, we design a kind of space camera image simulation system based on the working principle of TDICCD space camera. The system obtained the image data through USB bus interface. The image data transfer through the SRAM cache. To realize the permanent storage, the image data are stored in FLASH. This system may realize the change of camera line frequency and image size, so it can simulate different models of space camera. The experimental results show that the speed of data download comes to 40 MB/s from USB interface, and the image display by the space camera ground detection system is consistent with the original image sent by the host computer, without loss of data and error conditions. The camera image simulation system is flexible, stable and reliable performance, wide application range.关键词：image simulation system;USB;FLASH;assembly line
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发布时间：2020-08-12 - 摘要：4G-LTE high definition explosion-proof camera system is designed for petroleum, chemical and other high-risk environment. The most difficult point of device design is balancing the equipment features and explosion-proof performance. Based on explosion-proof theory, the design difficulties are equipment circuit capacitance and 4G-LTE transmit power. By increasing the capacitance limitation and reducing circuit, we can solve the high energy storage of explosion-proof circuit. 4G-LTE high definition explosion-proof camera system uses two half-wave dipole antenna array to maximize the transmit performance of device. Software protection achieves double explosion protection. After redesign, the two half-wave dipole antenna array can also enhance 9% effective isotropic radiated power than common antenna and the device can reduce 50% capacitance.关键词：wireless camera;basic capacitor circuits;storage capacitor design;double half wave dipole antenna array
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发布时间：2020-08-12 - 摘要：The just noticeable difference (JND) in luminance is one of important characteristics of the human visual system (HVS). With the popularity of computer display, the JND in luminance has important application value for viewing the image details under the computer display environment. In this paper, generated luminance stimuli using liquid crystal display (LCD) with 10 bit graphic card, the JND for 27 background luminances were measured by the psychophysical experiment on luminance matching. Experimental results show that the ratio of the JND and background luminance is about 0.017 at the moderate background luminance from 11.89 cd/m2 to 142.3 cd/m2, that follows the Weber's law, and the ratio of the JND and background luminance is decreased with increase of the background luminance at lower background luminance from 0.38 cd/m2 to 9.36 cd/m2. The measured results of JND for luminance of human visual system on liquid crystal display under moderate background luminance are consistent with Koenig and Brodhun's results using traditional method.关键词：computer vision;visual optics;weber's law;visual matching;just noticeable difference;luminance
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发布时间：2020-08-12
Display and Image
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