摘要:Photoresponsive liquid-crystalline block copolymers are a kind of block copolymer containing photoresponsive liquid crystalline moities. As a novel kind of functional material, they combine the characteristics of photoresponsive liquid crystals and block copolymers. The research in this field mainly focus on azobenzene-containing liquid-crystalline block copolymers. In this paper, the photoresponsiveness of liquid crystalline materials and the microphase separation of block copolymers are briefly introduced. Then the mechanism of photoresponsive feature, the process of microphase separation and their regulation are explained in detail. Finally, potential applications in photonics, nanotemplates, nanoparticle arrangement and micelles are also discussed.
摘要:The UV polymerization-induced phase separation (PIPS) method was introduced to prepare the reverse-polymer network liquid crystal (PNLC) films with difunctional acrylate as main structure from the system contained photo-curable monomers, liquid crystal (LC) and photo initiator.The concentration of the photo-initiator 1-hydroxy Cyclohexane benzophenone (IRG184) was changed and the type of liquid crystal cells and their effects on the electro-optical properties of the reverse-polymer network liquid crystal (PNLC) were tested by LCT-5016.The results showed that the electro-optic curve (in terms of the properties such as threshold voltage and operating voltage) of the reverse-PNLC film was the best, when the condition was optimized as follow: the intensity of UV light was 18 mW/cm2, the main wavelength was 365 nm, the temperature was between 25~30 ℃, the concentration of the photo-initiator IRG184 was 0.2%, the propylene monomer with double function groups was chosen as the photo-curable monomers, and the mixture was filled in the reverse parallel arrangement cell with 7 μm thickness.
摘要:Four lateral fluorinated three-ring diester liquid crystal compounds containing cyano group were synthesized from 4-alkylbenzoic acid, 4-hydroxybenzaldehyde and 3-fluoro-4-crynophenol.Their structures were confirmed by NMR,MS and IR and the phase transition temperature, Δε and Δn of these compounds were also tested.It is found that all of these liquid crystal compounds show nematic phase during heating.The measurement of physical properties indicate that the compounds have higher clearing point, lager Δε and Δn and wider range of nematic phase.
关键词:liquid crystal;diester;fluorinated;cyano group
摘要:By analyzing massive slow charging samples, the cause of slow charging was found, and on this basis, experiments were designed to improve the defect.The analysis shows that the cause of slow charging was the large altitude variance between color filter pixel and black matrix, which would cause rubbing weak area in rubbing process.The result of experiments showed that adding over coat on color filter could obviously decrease slow charging, but it was not suitable for production.Furthermore, by using high pretilt angle polyemid, and controlling delay time between polyemid process and rubbing process, the slow charging ratio could be effectively decreased from 28.2% to 0.2%, laying the foundation for a stable and efficient production of enterprises.
摘要:The UV stability of liquid crystal compounds containing tolane group was studied.It showed that the threshold voltage and birefringence of the liquid crystal decreased after 200 minutes of UV exposure. And it indicated that UV degradation of the liquid crystal depended on not only the absorption wavelength but also the detailed molecular constituents.The UV stability of liquid crystal with different terminal groups and linking groups were analyzed.The measured data showed that the diphenyl acetylene compounds with NCS terminal group exhibited a better UV stability than those with CN terminal group.The compounds with 1,4-cyclohexyl linking group were better than those with -COO- linking group or with none linking group.
摘要:Polymer-stabilized blue phase liquid crystal (PSBPLC) shows great potential application in displays and photonic devices due to its properties of submillisecond response time, optical isotropic status, and alignment free.A multi-dopant material system for polymer-stabilized blue phase liquid crystal is proposed.The driving capacity of PS-BPLC can be improved by doping N-vinylpyrrollidone (NVP) and polyaniline functionalized graphene (G-PANI).With the dopant optimization, the Kerr constant of PS-BPLC is increased by 68%, and the response time, hysteresis and residual birefringence have no degradation.
摘要:Image sticking is a display defect of TFT-LCD.The problem is to judge the level of line image sticking in cell in a short time.Generally, image sticking is related to dielectric anisotropy of liquid crystal.In this paper, 4 LC mixtures which have the same dielectric anisotropy are used for image sticking research.The line image sticking level of TFT-LCD using the 4 kinds of LC mixtures are evaluated.The relationship between LC mixture composition and line image sticking is analyzed. The use of -CF2O- and -COO- type of single can lead to line image sticking.In this paper, a method of measuring the strength of image sticking by testing the drift of V-T curve in DC voltage is explored.The principle of this method is analyzed.The experimental shows that when the rate of changeis less than 5%, line image sticking is slight, when larger than 10%, line image sticking is serious.This method can be carried out in Cell, and the test time was significantly reduced, which has the significance for improving the efficiency of the liquid crystal developing.
摘要:Simple head props used in clinical ophthalmology limit the distance between the doctor and the patient to arm's length, so that it cannot be utilized in adaptive optics retinal imaging system which is big and heavy.A two degree-of-freedom head prop is designed to support the subject's jaw and to make the subject's pupil align more quickly and comfortably in adaptive optics retinal imaging system. Self-locking trapezoidal screw in vertical movement and high transmission efficiency ball screw in horizontal movement were used with two stepper motors providing power.The electronics design of the control system based on PIC16F877A was completed.A MPLAB-Proteus co-simulation experiment was conducted and the result shows that the system can do the control in realtime to make the motor start, stop, turn and speed.The designed head prop can move in the vertical direction and the horizontal direction at a minimum of 100 μm/s and improve the positioning accuracy to 20 μm, meeting the requirements of the adaptive optics retinal imaging system.
关键词:adaptive optics retinal imaging;head prop;screw;microcontroller;stepper motor driver
摘要:Using the self-assembly properties of liquid crystal materials, a cholesteric phase liquid crystal 3β-Hydroxy-5-cholestene 3-oleate (CLC) is doped into the active layer of P3HT:PC61BM of organic polymer solar cells to manufacture photovoltaic devices with different doping proportion.The result shows that the efficiency of the device is highest when the CLC doping ratio is 0.3%.In conclusion, the self-assembly properties of CLC can promote the active layer molecules to be arranged more orderly during its crystallization proceeding.The effective crystallization results in a reduction of the molecular clusters and the layer defects in the active layer; and therefore it is useful to form a well transport channel for carrier transport. With the proper doping ratio, a high shunt resistor and fill factor of the device are obtained.The performance of the device is improved.
关键词:cholesteric phase liquid crystal;polymer solar cells;active layer ordering;fill factor
摘要:Due to the characters of high field effect mobility, good uniformity on large area and amorphous, indium-gallium-zinc-oxide thin film transistors is considered to be a new drive technology for the displays with large size and flexible character.However, the metal contact oxidation between source/drain electrode and active layer will increase the contact resistance and cause performance degradation.IGZO film without annealing has the characters of low oxygen content, more oxygen vacancies and high electrical conductivity.This article proposed using IGZO film without annealing as drain/source electrode buffer layer to reduce the contact oxidation and reduce the contact resistance.Experimental results indicated that the best performance of device can be obtained, when inserting 4 nm IGZO buffer layer, the mobility improved by 11.6% and the threshold voltage reduced 3.8 V compared with the device without buffer layer.In conclusion, the buffer layer can effectively improve the performance of device.In addition, using the same material with active layer as buffer layer can simplify the process compared with other material as buffer layer in industrial production with single rectangular target.
关键词:thin film transistor;InGaZnO;contact resistance;buffer layer
摘要:In order to achieve a higher resolution, higher aperture opening ratio, low power consumption TFT LCD product, the impact of different factors was analyzed. The alignment film printing quality control was strengthened, meanwhile factors involved in the process were researched and analyzed. The printing and drying conditions of alignment film, the production process of APR plate, alignment film thickness change and contraction rate, opening Ratio of APR were optimized. The method was found to control PI printing quality. Experimental results indicate that: the production line management and control scheme of TN product image quality improvement was determined by optimizing the film printing and drying conditions. APR protection film can improve Zara Particle 2% reduction, Scratch 1% reduction. Based on the orientation film thickness promotion, product segment difference and Image Sticking can be improved, meanwhile the contrast was improved 30-120 and Zara Particle 30% reduction. Through the optimization of APR mesh and opening rate, the incidence rate of sand mura was reduced to 0%.
摘要:The anti-reflecting structure and its performance of capacitive touch-display modules was studied.An analysis and comparison of several current anti-reflecting technologies of the touch-display modules were made.The results indicated that: for current modules, the inner reflectivity can reduce about 3.8% by the non air-gap technology and to lower than 2% by the super AMOLED and CBD technologies, so the readability under bright circumstance of the corresponding products can be improved effectively.In addition, two improved anti-reflecting structures respectively for LCD and OLED module were also provided. For the LCD module, the front polarizer was just laminated to the rear surface of the touch panel instead of the LCD surface, and the inner reflectivity was reduced to about 4.5%, so its readability under bright circumstance would be improved effectively and its low price would also be kept.For the OLED module, instead of attaching to the OLED itself, the circular polarizer was assembled to an OGS touch panel which would reduce the thickness of the module, and the inner reflectivity of the module was also reduced to about 1.8%.Because there was no need of OCA lamination, the price of this kind of modules would be lower than current super AMOLED modules.
摘要:The electrical properties of TFT-LCD are so significant especially for the leakage current at photo state (Photo Ioff).In this paper we investigated the factors which could affect the Photo Ioff in order to improve the TFT-LCD performance.A measurement method has been proposed based on experiment results.The black matrix (BM) photo resist (PR) has been used to shield different parts of TFT channel, then the difference of electrical properties could be confirmed through TFT I-V curve.According to the experiment results, it is quite easy and effective to decrease the photo Ioff value by optimizing the gate line width.Finally we used this method on 54.6 cm(21.5 in)TFT LCD samples.Optimized results showed that the gate line should be widened 1.5 μm based on the original design.The actual result was proved though TFT characteristic measurement results, the photo Ioff decreased to 9.50 pA from 14.08 pA.It turns out that the proposed method is quite effective in the practical production process.
关键词:thin-film transistor liquid crystal display;test method for thin-film-transistor;photo off-leakage current
摘要:In order to enhance understanding of photoresist ashing and give reference to 4 mask process improvement, the effect of each film layer on photoresist ashing was researched.In the same ashing process condition,ashing rate of samples with different film layer was measured by α-step profiler, and the mechanism of test result was analysed.Experimental results indicate that a-Si can decrease ashing rate, SD metal can increase ashing rate, gate metal has no effect on the ashing rate.And for normal film structure TFT array substrate, the bigger SD pattern density is, the smaller ashing rate will be. If SD pattern density increased 1%, ashing rate would decreased 14 nm/min.Because of influence on ashing plasma, a-Si and SD metal have an effect on ashing rate.
关键词:thin film transistor array process;four mask;photoresist;ashing
摘要:In order to realize ultra-wide-angle image for automotive camera, an ultra-wide-angle automotive camera is designed to solve comprehensive monitoring perspective issue in reversing image system.Its applied such as image sensor and ultra-wide-angle imaging technique, hardware circuit design and the EMC protection of interface are investigated. We opted for a Omnivision-based CMOS image sensors OV7962 according to the current auto companies' requirements. The lens adoptes the new staring panoramic imaging technology—fish-eye lens imaging and calculating the focal length and resolution of the lens by matching the parameters of image chip. The hardware circuit design and EMC protection of the camera are tested and improved.Experimental results indicate that the camera can achieve 210° ultra-wide-angle image and the EMC protection of interface has passed the ISO-7637-2 pulse 5b testing standard.It can satisfy the comprehensive monitoring around perspective requirements of reversing image system.In addition, this automotive panoramic camera also has the advantages of low cost, stable performance, high resolution, as well as super night vision.
关键词:fish-eye lens imaging;ultra-wide-angle;CMOS image sensors;electro magnetic compatibility
摘要:The design of the experimental platform about microprocessor-based transformer protection is based on TMS320F28335 and STC12LE5A60S2 in order to make the staff to understand the principles of transformer protection deeply and strengthen the work of transformers' protection.The TMS320F28335 acquires and processes the real-time data about voltage and current of both sides of the transformer,undertaking the tasks of calculation,communication and controlling the switch quantity.The STC12LE5A60S2 receives data from the DSP through the serial communication and controls TFT LCD module MD070SD.The MD070SD can be controlled to show 3 kinds of interfaces: setting interface /data display interface and the protection test interface through an external button.This paper presents the hardware control circuit both of the serial communication and the liquid crystal display, and gives a detailed account of the LCD module's 3 display interfaces.Results of the tests show that the platform can achieve the function of data display and protection test reliably, its real-time and visibility can meet the display requirements of the protection equipments for transformer.
关键词:microprocessor-based transformer protection;experimental platform;interface design of MD070SD;adjustment of LCD backlight
摘要:A FPGA-based SOPC embedded system timing controller is designed for some LCD panel driver chips which only bonding with source and gate circuits.It uses FPGA logic circuits to implement the functions such as LVDS video signal decoding, grayscale expansion, RSDS signal encoding, and control timing conversion display.Through the serial port setup parameters in FPGA soft-core Nios II, GAMMA and VCOM voltage can be programmed.Those parameters have power-down protection.The timing controller also adds BIT detection circuit which check the operation status in real-time.This high integration, low power consumption, simple structure timing controller circuit is suitable for special applications with high use value.
摘要:In order to improve the uniform brightness of Active Matrix Organic Light Emitting Display (AM OLED) caused by the difference characteristic of TFTs' among pixels, digital driving methods of Address While Display (AWD) based on accumulated lighting using 11 equal weight subfields and order dither to realize 256 gray scales was investigated and implemented on AM OLED module of 5.5 inches with pixel circuit of 2T1C.The experimental results of gray scales (0~255) show that digital driving is insensitive to gray scales and the maximum value of non-uniform brightness is 28%.It is increased as gray scale increasing and the maximum value reaches to 133% by using analog driving.The uniform of displayed image using digital driving is superior to that using analog driving and easy to be implemented based on pixel circuit of 2T1C.The complexity to pixel circuit and processing cost will be decreased.
摘要:Flash memory is often used as display information storage devices of embedded large screen display system, however flash memory exists errors such as bit upset in reading or writing operation, that will bring the hidden dangers to normal display of system.Flash memory error rate and display data access characteristics are analyzed to design the display data error control under flash memory.Considering the characteristics of embedded control system, a (31,26) cyclic Hamming encoding and decoding circuit is designed, which can reduce the error rate of an order of magnitude, and enhance the ability of anti burst interference and anti random interference, at the same time have the design of low complexity.
摘要:In order to predict the quality of stereoscopic images accurately, an objective stereoscopic image quality assessment method based on edge and characteristic point matching is proposed. Firstly, for the quality assessment, a method that takes the edge information into account is presented, which is based on the plane image quality assessment method; secondly, for the stereo sense assessment, a stereo matching method is used for extracting stereo sense index. Finally, according to quality and stereo sense, a total evaluation index is proposed based on an appropriate weighted method. The experimental results indicate that compared with other methods, the overall Pearson linear correlation coefficient indicators are all above 0.94, which indicates that the proposed method can achieve higher prediction accuracy.
关键词:stereo image processing;quality assessment;edge;stereo sense
摘要:A new mathematical modeling method based on smoothing filter is proposed for the latest virtual LED display screen and a new control method is proposed for the application of the new modeling method.Compared with traditional virtual display system, system with new mathematical modeling and control method can decrease the need of the data bandwidth and increase the gray scale of the virtual display system.Firstly, the article analyzed the imaging principle of LED screen and explored the nature of virtual display and gave the evaluation criteria of the LED screen which include resolution and gray scale.Secondly, the article introduced the implementation of the traditional virtual display and its problems.Thirdly, the article proposed a new mathematical modeling method for the latest virtual LED display screen and predicted the feasibility of new method.Then, the article used a LCD screen to simulate the feasibility of new method and used the virtual LED screen to verify the result of new control and modeling method.At last, the article compared traditional and new method.The experimental results indicated that by using the new control and modeling method, the image displayed on virtual LED screen is vivid and the detail of image is fully displayed.Therefore, the new method of control and modeling can be used in virtual LED screen.
摘要:Due to the problem that the existing method of objective quality assessment algorithm is not suitable for multi-distorted images, the quality assessment method for multi-distorted images was studied in this paper.On the basis of analyzing capability that the singular vector and edge information representing visual feature, an algorithm of image quality assessment based on the singular value decomposition of edge information was put forward.Firstly, the edge information of the reference image and distorted image which is sensitive to visual information was extracted by using the Sobel operator.Secondly, the singular value of the edge information of two image was decomposed, then the angle between the singular value was calculated to describe the quality of the distorted image.Finally, the algorithm applied in this paper are verified by more than 450 distorted images in LIVE Multiply Distorted Image Quality Database, and the algorithm was compared with the MSE,PSNR,SSIM,CSSIM method.Experimental results show that the algorithm is more consistent with human subject scores and has greater stability for multi-distorted image than traditional methods.Through comparison with the time efficiency, the proposed algorithm can basically meet the practical demand, and the algorithm is more usability.
关键词:edge information of image;singular value decomposition;image quality assessment
摘要:Velocity estimation and vehicle detection from satellite images is widely used in the domain of traffic monitoring, battlefield analysis etc.But most of the algorithms in this area are either manual or incorporating ancillary data.A new method has been developed to extract vehicles automatically and determine their speeds based on computer vision.First of all, the “Ghost” phenomenon of moving targets is analyzed by considering the structure of Quickbird panchromatic and multispectral focal plane.Normalized differential vegetation index, image segmentation and morphological gray scale reconstruction are combined to realize accurate vehicles detection in panchromatic image; subsequently image matching is applied to extract vehicles in the multispectral image based on the vehicle positions in panchromatic image.The speed can be calculated by using the vehicle extraction results and time intervals between panchromatic and multispectral images.Finally, this approach was tested on several images of Quickbird covering different backgrounds and can obtain a detection rate as high as 90%.The performance shows that the algorithm is practicable and valid.
摘要:An adaptive median filter based on slope is proposed to remove the impulse noise effectively.The algorithm based on the adaptive median filter algorithm, uses difference of slope to determine noise.Compare with traditional algorithms, it performs better when the noise intensity gets high.Meanwhile it solves the difficulty of filtering noise block.The result shows that the algorithm can remove impulse noise effectively and protect image details well.
摘要:For enhancing fusion accuracy of multi-modality images, an adaptive image fusion algorithm based on local nonsubsampled shearlet transform (LNSST) and pulse coupled neural networks (PCNN) is proposed.First,source images are decomposed to multi-scale and multi-direction subband images by LNSST.Secondly, local area singular value decomposition in each subband image is done to construct a local structure information index which is served as linking strength of each neuron in PCNN.After the fire processing of PCNN, new fire mapping images of all the subbands are obtained, the clear objects of subband images are selected by the compare-selection operator with the fire mapping images pixel by pixel and then all of them are merged into a group of new clear subband images.Finally, fused subbands are reconstructed to image by local nonsubsampled shearlet inverse transform.Some fusion experiments on several sets of different modality images are done and objective performance assessments are implemented to fusion results.The experimental results indicate that the proposed method performs better in subjective and objective assessments than a few existing typical fusion techniques in the literature and obtains better fusion performance.
摘要:There were many traditional methods of image quality assessment.But they were not specific evaluation method for super-resolution restoration.So far there is no uniform evaluation criteria for super-resolution restoration, which largely restricted the development of super-resolution restoration algorithm.For the disadvantage of the traditional super-resolution restoration evaluation system only concerning about a particular aspect of the statistical properties of the image, this paper proposed the super-resolution restoration evaluation method based on SSIM_NCCDFT, which combined the gray value and contrast of the spatial domain and the autocorrelation of frequency domain.Therefore, the proposed evaluation method can evaluate the results of the super-resolution restoration in both spatial domain and frequency domain. Experimental results showed that SSIM_NCCDFT can accurately reflect the degree of image degradation.Relative to PSNR, SSIM_NCCDFT reflected both frequency and spatial accuracy.SSIM_NCCDFT was a more comprehensive evaluation.The evaluation method of super-restoration method based on SSIM_NCCDFT proposed in this paper can evaluate the results of the super-resolution restoration in both spatial domain and frequency domain.It got more comprehensive evaluation results.It can evaluate the image noise and blur.Furthermore this evaluation method has some significance for super-resolution restoration evaluation.
摘要:In order to improve the skin detection in 3D virtual keyboard, this paper establishes a new skin detection method based on the color space and the background difference.Both the robustness and the speed of the skin detection are promoted after the replacement of the origin method by the new method.Firstly, this paper presents the theory and the detailed steps, and gives the results of the previous method.Then, some problems are presented and the paper gives much advice about improving the speed by analyzing the theory.Combining the HSV color space with the YCrCb color space helps to improve the operating speed.Also, the paper makes the background difference as an adjunction to the color space, and solve the problems, such as the negative effects of the interference colors and the jewelries, that cannot be overcome just by the color space.The experience shows that, after applying the new method, the operation time is shortened by 28.27% and the average error of finger recognition is lower than 2%.All of these indicates that the new method meets the requirement of promoting the robustness and the speed of the skin detection.
关键词:3D virtual keyboard;mixed color space;codebook background difference
摘要:In order to meet the demands of high dynamic range for CMOS camera under the mode of global shutter, a camera system is designed based on CIS-2521 sCMOS image sensor device.By analyzing the readout structure characteristics of pixel of CIS-2521 chip and the driving timing under the mode of global shutter, we choose FPGA with DDR3 as the processing structure and complete the design of SOPC including the control of imaging parameters, driving timing of sCMOS, capturing the image data, image preprocessing and so on, and introduces the function of every module.The designed camera realizes the imaging output of 50 frames of 2 560×2 160 pixel and 14 bit depth with high sensitivity, high dynamic range per second by the imaging test, and it meets the requirement of scientific imaging.