最新刊期
期 5 ， 2011
- 摘要：A cholesteric liquid crystals (Ch-LCs) polymer film with broadband reflection was fabricated induced by UV Absorbing Dye (UVAD). The results demonstrated that the gradient of UV light intensity forms cross the polymer film by adding the UV-absorbing dye to the Ch-LCs acrylate mixture, resulting that the pitch gradient forms in the Ch-LCs polymer film. After UV irradia- tion, a UVAD doped Ch-LC film can reflect incident light with the bandwidth over the visible light spectrum. The Ch-LCs polymer film with broadband reflection may be applied in at smart windows for the control of solar light and optical functional films.关键词：cholesteric liquid crystals;pitch gradient;broadband reflection;UV absorbing dye
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发布时间：2020-08-12 - 摘要：Azobenzene containing side-chain liquid crystalline polymer was synthesized by hydrosilation reaction of poly(methylhydrosiloxane) with the azo monomer. The chemical structure and its liquid crystalline properties were investigated by FITR, DSC and POM with a hot stage. Photo-alignment treatment was performed on the polysiloxane film by using a linearly polarized light source with the wavelength of 473 nm. A static contact angle mea-surement was carried out and the surface free energy was also calculated from the contact angles of a drop of water on the polymer film. The water contact angles was decreased from 94.5° to 76.5° after the light irradiation. We conclude that the changes in the hydrophilic of LC polymer were influenced by the surface compositions upon the photoinduced reorientation of the azobenzene side groups perpendicularly towards the film surface, which was confirmed by conoscopic POM observation results.关键词：azobenzene;liquid crystal;photoinduced orientation;polysiloxane;surface free energy
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发布时间：2020-08-12 - 摘要：On n-Si(100) substrates, the Si1-xGex films were deposited by RF magnetron sputtering technique. AES spectra determine that Ge content in the Si1-xGex film is 17% approxi-mately. The Si0.83Ge0.17 films were doped with phosphorus at high temperature through thermal diffusion to fabricate n-type polycrystalline films, that is, the n-poly-Si0.83Ge0.17. And a Co film was sputtered on it. Thus, the Co/n-poly-Si0.83Ge0.17/n-Si Schottky junctions were made. Rapid thermal annealing (RTA) was conducted on these junctions from 300 ℃ to 600 ℃. The variable temperature I-V testing has been performed on the annealed Co/n-poly-Si0.83Ge0.17 Schottky junctions. It is found that, with the test temperature increase, the Schottky barrier height (SBH) difference of samples annealed at different RTA temperatures becomes less. And the sample annealed at 500 ℃ has the least apparent SBH. As a whole, the SBHs increase and the apparent ideality factors decrease with the test temperature increasing. Based on the model of inhomogeneous distribution of SBH, a reasonable explanation has been fulfilled on the experimental data.关键词：variable temperature I-V testing;Schottky junction;rapid thermal annealing;ideality factor;inhomogeneity of Schottky barrier height
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发布时间：2020-08-12 - 摘要：High brightness red phosphor YAx(VP)O4 ∶Eu3+ and Y0.94－yLny(VP)O4 ∶Eu3+0.06(A= Mg,Ca,Sr,Ba;Ln=La,Ga) particles were prepared by coprecipitation process. The sample was investigated by X-ray diffraction (XRD),scanning electron microscope (SEM),excitation spectra and emission spectra. The particles were spherical shape. Aggregation between particles was not observed. The phosphor particles had very high emission intensity. The main excitation peak of the particles was 300 nm. The main peak for the emission spectra was 620 nm. Emission intensity of YAx(VP)O4 ∶Eu3+ phosphor doped with little Sr and Ba could be improved. Emission intensity of YAx(VP)O4 ∶Eu3+ phosphor showed a decreasing trend with Ca and Mg. Emission intensity of Y0.94－yLny(VP)O4 ∶Eu3+0.06(Ln=La,Ga) could be improved evidently when doped with La3+ and Ga3+. The phosphor showed red emission with good color purity under 300 nm light excitation. This phosphor is a good substitution for (Y, Gd)BO3 ∶Eu3+ in PDP.关键词：doped;alkali earths;rare earths;Y(VP)O4∶Eu3+
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发布时间：2020-08-12
Material Physics & Chemistry
- 摘要：Based on the Bragg reflection of cholesteric liquid crystal,a structure is designed, which is formed by opposite charities of cholesteric liquid crystal of red, green and blue to enhance the reflectivity. This thesis reports the reflective spectra of LCD cells by the 4×4 matrix method. With the comparison of reflective spectra between solo RBG three-element-colors stack (three-layers) and the opposite RBG three-element-colors stack (six-layers), the calculated reflectivity is given by changing the parameters of liquid crystal. In the best condition, the reflectivity of a six-layers LCD stack reach the maximum of 98.91% while the reflectivity of a three-layers LCD stack reach the maximum of 64.95%. This thesis also reports the result of chromaticity analogy of the LCD stack, which ranging from 5 240.9 K to 7 029.8 K. Overall, in the best condition, the chromaticity of a six-layers LCD stack is 6 285.7 K.关键词：cholesteric liquid crystal;stack;spectrum;4×4 matrix
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发布时间：2020-08-12 - 摘要：Adopting LED as the light source, LCD TV has significant advantages over adopting Cold Cathode Fluorescent Lamp (CCFL). Light guide plate (LGP) with a two-dimensional array of dots scheme is the key to the design of the LED backlight unit (BLU). A LED BLU with 1.066 8 m in diagonal and 4 mm in thickness, using incidence structure with four-side light sources is proposed in this paper. Considering the complexity and time-consuming process of the large scale LGP dot-pattern design, the method of simplified model is introduced which is the simplification of the LGP and the LEDs. The optimization result between the simplified model and the actual model can be ignored. The LGP luminance uniformity reaches up to 90% and the extraction efficiency is around 50%. Adopting the same method to a BLU with 1.422 4 m in diagonal and the thickness of 3 mm, it also achieved a good result. The luminance uniformity reaches 85% and the extraction efficiency is around 50%.
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发布时间：2020-08-12 - 摘要：The dependence of Push Mura and cold bubble on spacer density was studied. The experimental result shows that the strength of panel can be increased through increasing spacer density, but cold bubble will happen if spacer density is too high. When spacer density is controlled in suitable window, Push Mura can be greatly decreased, cold bubble does not happen, without affecting the optical properties of the panel.关键词：LCD;improvement;spacer
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发布时间：2020-08-12 - 摘要：As substrate materials rigid glass is commonly replaced by PET plastic films for preparing flexible LC cells, the traditional process may cause nonuniform thickness and trap air bubbles in LC cells which deteriorate property of flexible LC device. These problems can be effectively solved by a rolling technique. The detail process has been described in this paper. It was found that the viscosity of solution was reduced by heating the two substrates which avoids the interfusion of air bubbles in the solution and results in LC cells with uniform thickness. 7 cm2-sized flexible reflective bistable LC cells are prepared successfully by polymer dispersed cholesteric liquid crystal method. Polymer dispersed cholesteric liquid crystal texture is studied by polarizing microscope. Electro-optical of flexible liquid crystal cell is measured by ultraviolet. The film provided with max reflectivity 22.8%, contrast 2.259, threshold voltage 78 V and saturation voltage 99 V.关键词：polymer dispersed cholesteric liquid crystal;flexible LC cell;rolling process;electro-optical property
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发布时间：2020-08-12 - 摘要：As to the TFT-LCD and other display monitors, Mura is a relatively normal defect which will degrade the display quality greatly. The analysis of the unknown Mura, indicated that the active remain in the Fan-out area are the main reason of the unknown Mura, and a novel method is introduced to solve this defect by changing the condition of Photo process. The mass production feasibility of this method has been demonstrated through experimentation.关键词：unknown Mura;fan-out area;active remain;exposure condition
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发布时间：2020-08-12 - 摘要：Using NPBX with 3% DSA-ph doped as the emitting layer, BCP or TAZ as a hole blocking layer, Alq3 or Bphen as an electron transport layer, a set of blue light-emitting devices were fabricated. A group of high efficient blue OLEDs were got by adjusting the combination between the different hole blocking layer and the electron transport layer. The result shows that when the hole blocking layer is TAZ and the electron transport layer is Bphen, the performance of the device is the best. It has a maximum current efficiency of 4.59 cd/A at 5 V and maximum brightness of 6 087 cd/m2 at 12 V.关键词：organic light-emitting diodes;electron transporting;hole blocking;efficiency
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发布时间：2020-08-12
Device Technology & Physics
- 摘要：This paper proposed a test scheme for a dedicated, multi-channel, large capacitor load LCD driver chip. The 12.5 MHz basic clock, control vectors for state change and frame frequency selection are provided by the FPGA, decreasing data is written to registers in the chip. With 200 pF capacitive load, the output signal range can realize 1 024 gray level and over 12 V voltage swing. Through testing the DAC and output buffer module in the chip, it is found that charging speed of the buffer to miller capacitor and the DAC to sampling capacitor cause the problem of longer full-swing rising/falling time and nonlinear output. It can be improved by reducing the on-chip convert resister or sampling capacitor to some extent. Finally, an improvement scheme is proposed, which uses switched-capacitor DAC and Class-AB output buffer error amplifier.关键词：LCD;driver chip;current steering DAC;class-AB output buffer;test
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发布时间：2020-08-12 - 摘要：A display program of LCD display module controlled by DSP has been adopted, and the systems hardware and software are analyzed.This display program lies in timing simulation of writing and reading by using general I/O port. Using specific implementation methods of C language, and rich display of LCD module, a better interface between DSP and LCD display module is realized,and has been applied in the actual workplace. Test shows that the display system is stable, and has better display quality and faster refresh rate, can achieve the desired objectives.关键词：DSP;LCD;operation timing;clearing the screen;C language
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发布时间：2020-08-12 - 摘要：Regarding TIs DSP chip TMS320F2812 as the main chip, a kind of LRG(Laser Rang-Gating) imaging system based on the DSP is designed. The controller has LCD display and key setting function. The system status and parameters can be displayed on the LCD. The function and hardware structure of the controller, and software flow design has been given. The practice proved that the controller has the advantages of simple structure, delay time precision and real time. The controller satisfied perfectly the laser active illuminated imaging system.关键词：range-gating;TMS320F2812;synchronization control;LCD display
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发布时间：2020-08-12 - 摘要：In order to satisfy the requirement of miniature and low-power dissipation for the array CCD in the applications of traffic and surveillance, an image acquisition system based on array CCD with FPGA/SOPC architecture is designed. This system includes FPGA as the controlling module to collect the Video signal, build-in NiosⅡ microcomputer control unit (MCU) as the image processing unit, and μC/OS-Ⅱ operating system as the manager of multiple tasks. This system extends universally and satisfies the requirement of miniature and low-power dissipation.关键词：CCD;FPGA;image-sensor
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发布时间：2020-08-12 - 摘要：Aimed at the necessary of digital video convert from RGB to BT.656 on many occasion, a realization scheme based on FPGA was put forward. The key technology and modules of system was analyzed. The status transfer mechanism was used to accomplish the production of BT.656 video timing; The linear and circular compensation method was applied to avoid the color distortion when conversion from RGB to YUV; The FIFO circuit with function of input and output selection control was employed to resolve the speed matching between input data and output data. The emulation result shows good purpose while an application example is introduced to indicate its broad prospect in video signal conversion.关键词：RGB;BT.656;status transfer;linear and circular compensation method;FIFO
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发布时间：2020-08-12 - 摘要：To satisfy rigid performance specifications, this paper provides a design of performance testing system for photoelectricity tracker based on video emulation.It can give a result to evaluate the performance of a photoelectricity tracker by adding emulation video,storing pictures and analyzing images.关键词：video emulation;photo-electricity tracker;testing
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发布时间：2020-08-12 - 摘要：In order to replace the PC system for high frame rate digital image acquisition and display based on camera link interface, an embedded system based on SOPC and NiosⅡ has been developed. System construction is designed according to functional requirement, and the design method for each functional module of the system is presented. Then signals of interface module, image data storage and process module have been programmed and simulated. Finally, the experiment of system for high frame rate digital image acquisition and display is described and analyzed. Experimental results indicate that high frame rate image which resolution is 128×128, and transferred at 1 230 frames/s can be grabbed, processed and displayed by designed system. It can satisfy the system requirements of lower cost, saving space, improving system stability and work bandwidth.关键词：SOPC;high frame rate camera;FPGA;image acquisition
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发布时间：2020-08-12 - 摘要：In regard to the issues including information can not be update off-line, the splash screen which was caused by conflict between reading-writing frame cache and scanning, an intelligent LED display control system design method was presented based on ATMEGA32. In hardware section, MBI5026 was used to enhance the driver ability, and ADXL202 was used to build up the abilities of gravity recognition and automatic information display rotation. In software section, Chinese input-PINYIN, real time information display was available in the program, a scanning optimal model is also established. By setting up the parameters of numbers of row-column and numbers of scanning optimally, the scanning speed can be improved to its maximum capacity. Experimental results show that the system has great advantages, including the brightness can be adjusted intelligently, the external circuit is simple and easy to install and upgrade. In short, it is an excellent application for engineering.关键词：MBI5026;ADXL202;scanning optimal model;Chinese input-PINYIN
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发布时间：2020-08-12 - 摘要：The LCD driver in Linux based on ARM11 embedded system was studied. A method of LCD driving design on the basis of the framebuffer, and two methods on the basis of reading and writing GPIO directly were analyzed. The advantages and disadvantages of the three LCD drivers were summarized by testing. A LCD control mode was implemented by combining the framebuffer and direct both reading and writing GPIO driver. The application indicates that this method can obtain following advantages:faster speed, simpler driver and stronger transplantation.关键词：Linux;ARM11;LCD driver;Framebuffer;GPIO
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发布时间：2020-08-12 - 摘要：An IP core of ST7920 series 12864 LCM was designed meeting the Avalon MM interface specification, an NiosⅡ-based SOPC system was set up and the graphical and character display of LCD were realized. The system design and key technologies were introduced step by step following the sequence of development process. The hardware design of LCD12864 IP core was written in Verilog HDL, following the newest signal naming conventions for automatic type and interface recognition suggested by Altera, while detailed C driver code and program specifications were provided in the software design of LCD12864 IP core. An application program example of graphical display was also provided. The IP-based SOPC system has been proved feasible according to the actual experiment performances which get the desired results.关键词：NiosⅡ;LCD12864;ST7920;SOPC;IP core
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发布时间：2020-08-12
Driving & Controlling
- 摘要：According to the disadvantage of color distortion of color histogram equalization algorithm, a new image enhancement algorithm based on dark channel prior is presented. First, the dark channel image is done. Then the transmission map and the atmospheric optical components map are estimated. Finally the bright values of the pixels of the image are calculated according to the atmospheric model. An embedded high speed image enhancement processing system on high performance DSP TMS320DM6437 and FPGA was designed. Experimental results with real images shown that the system can improve the contrast and color of the image, restore the real color of the image, and effectively enhance the image, the running time of the program is shorter, so it can meet the requirements in the project.关键词：color image enhancement;embedded system;contrast;histogram equalization;dark channel prior
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发布时间：2020-08-12 - 摘要：Two new focus measure methods (Bevel and Mix operators) derived from gradient edge detection were proposed. The Bevel and Mix operators and correlation operator were respectively chosen as the focus measure method of coarse search and fine search. A new method of selecting suitable focusing region was presented. Then, mountain climbing search strategy with variable step (MCS), local-global search strategy (LGS) and general search strategy (GES) were proposed. Using a lens with focus length of 130 steps and focus depth of 2 steps, the three search strategies can shorten the focusing time from the full searchs 37 s to 3~4 s ,4~6 s and 3~5 s respectively. The experimental results show that, the method can meet the real-time and accurate requirements of airborne electro-optical imaging device.关键词：airborne electro-optical imaging device;focus measure function;image edge detection;focus areas;search strategy
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发布时间：2020-08-12 - 摘要：Marching Cubes (MC) algorithm has disadvantages of bad-surface of 3D surface model and triangle redundancy. To improve this algorithm performance, smoothing for iso-surface and edge deleting algorithm to simplify the meshes are presented. The direction smooth of the three-dimensional space on the iso-surface was used to replace the smooth of three-dimensional coordinates on the iso-surface, and the smoothness of the model surface was improved. Based on the edge deletion algorithm, a mesh simplification algorithm was designed to simplify the model surface mesh. Two groups of Magnetic Resonance (MR) data (hollow throat and cardiovascular system) were used to actualize three-dimensional surface reconstruction. Running examples show that the smoothed three-dimensional display has been improved significantly, and the clarity and realism of the structural details improved obviously. After 90% mesh of the model had been reduced, the model can still maintain the original features and good visual effects, and the ability of real-time interactive rendering was enhanced greatly, the interaction time was reduced evidently.关键词：marching cubes (MC) algorithm;iso-surface;smooth;3D reconstruction
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发布时间：2020-08-12 - 摘要：The traditional ground simulation system is usually developed with VC++, so the development is accordingly very complex. It can only show the data when performing satellite on-orbit state, or develop 3D display system with OpenGL and D3D technique which are very hard and time consuming. So, the paper gives a new design of the Satellite Ground Simulation System based on Virtue Reality 3D Display Model of Matlab which can make use of the existing model in Matlab to establish the mathematical model and the display system. The system has the 3D display function, the difficulty of the system development is also decreased.关键词：virtue reality;3D display;ground simulation system
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发布时间：2020-08-12 - 摘要：A new background reconstruction and moving foreground extraction algorithm is proposed for stereo video with static backgrounds. Firstly, based on the left and right foreground of moving region by using Frame-Difference method, the enclosing rectangles of the moving foreground areas are initialized, and the background is reconstructed based on the initial block. Then, the left and right moving foregrounds are separated by comparing the reconstruction of the backgrounds information with every frame images. The result of the experiments shows that it can achieve the segmentation accurately and reduce the stereo matching time and the information storage significantly.关键词：video compression;background reconstruction;foreground extraction;stereo matching
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发布时间：2020-08-12 - 摘要：In order to cut down the power consumption of LCD backlight and maintain the image quality, a modulation algorithm based on Local Mean (LM) and Local Standard Deviation (LSD) is proposed. The algorithm can dim the luminance of backlight effectively in dark and low contrast blocks and maintain the image quality in the bright and high contrast blocks. Meanwhile, backlight signals are smoothed to ensure smooth transition between each region and its surrounding regions,which makes images downy on the vision.关键词：LCD;dynamic backlight;local mean;local contrast
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发布时间：2020-08-12
Imaging Technology & Image Processing
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