最新刊期
期 3 ， 2015
- 摘要：In order to realize optical zoom system on the portable devices, the optical system without any mechanical moving part is necessary. Therefore, we established the electrically tunable optical zoom system using liquid crystal(LC) lenses and investigated the relation between the focal length of the LC lens, magnification of images, zoom ratio and the object distance. One LC lens can only have the function of focusing, therefore, first, we utilized two LC lenses to design the optical system and figure out the zoom ratio at different object distance. Second, we used three LC lenses to establish the system that the function of focusing and zooming can be controlled independently and it is similar with the mechanically tunable system. Experimental results indicate that by using three LC lenses with tunable lens power ranging from -11.3 m-1 to 24.9 m-1,we can achieve electrically tunable optical zoom system. The object distance of the system can be changed form 10 cm to 100 cm continuously and the zoom ratio is 6.5:1. According to the principles, we can achieve electrically tunable optical zoom system with different range of object distance and different zoom ratio by LC lenses with different tunable lens power range.关键词：liquid crystal lens;optical zoom system;focusing function
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发布时间：2020-08-12
Invited Paper
- 摘要：The Bragg reflection and optical rotatory power of cholesteric liquid crystal (ChLC) and blue phase liquid crystal (BPLC) are studied using finite-difference time-domain (FDTD) method. Firstly, the Bragg reflection of ChLC and BPLC is calculated, and the simulation results are discussed from the aspects of lattice structures and molecular arrangement. The effect of refractive index and pitch of liquid crystal on the Bragg reflection is also studied. The light leakage of the ChLC and BPLC sandwiched by the crossed polarizers is calculated, and the similar and different phenomena are analyzed by the optical rotatory power of liquid crystal.关键词：blue phase;cholesteric;Bragg reflection;optical rotatory power
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发布时间：2020-08-12 - 摘要：The reason for GOA unit defect is analyzed in the TFT-LCD manufacturing process, and the improving methods are given. The results show that the occurrence of the ESD is ascribed to excessive instantaneous release current of capacitance, leading to superfine wire melting, while the occurrence of the Channel Bridge and Open is related to the development effect, development direction and pattern density, which cause the abnormal channel photo resist. The design of electrostatic dispersion release makes the incidence of ESD reduce from 5.4% to below 0.04%. The design of adding Dummy Pattern in both sides of GOA unit prevents Channel Bridge, meanwhile the adjustment of Vacuum Dry extraction curve and the optimization of Soft Bake bottom temperature prevent Channel Open, which make the incidence of Channel Bridge and Open decrease from 13.4% to below 1.22%.关键词：gate driver on array;electro-static discharge;channel bridge;channel open;development effect
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发布时间：2020-08-12 - 摘要：Image sticking is one of the most important factors to evaluate the display quality of liquid crystal display(LCD), and most of the engineers studied the material composition and the LCD manufacturing process to improve the image sticking, but the previous research mostly based on the positive liquid crystal material. In this paper, the image sticking is mainly focused on the negative liquid crystal(LC) material which is driven by fringe electric field. First, the ion density and VHR are measured to compare the stability of the two kinds of LC material, and then the residual DC voltage and the Vcom voltage shift of the sample are measured to compare the characteristics of the negative LC with two PI materials so as to select the right combination. The experimental results show that the ion density of the negative LC is 39 times as much as the positive LC before UV curing. After UV curing, its ion density is 560 Pc/cm and its VHR variation is 2.7%; the residual DC voltage and the Vcom voltage shift with time of sample A-1 are the largest which use negative LC with PI1. Its residual DC voltage is 0.5 V and the Vcom voltage shift is 250 mV, and the residual DC voltage of samples which use negative LC with PI2 and positive LC are less than 0.2 V, of which the Vcom variation with time are within 50 mV. The ion density of negative LC material is high, and its stability is worse than positive LC material, image sticking appears in the negative LC material more likely. For the FFS driving mode LCD panel which using negative liquid crystal materials, it is beneficial to use the PI2 material to maintain a low residual DC voltage and low Vcom voltage variation, which are helpful to improve the image sticking.关键词：fringe field switching;negative LC;image sticking;polyimide
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发布时间：2020-08-12 - 摘要：With the development of liquid crystal display technology, the higher PPI is, the smaller pixel is. The improvement of transmittance is an important issue. Compared with positive liquid crystal display, negative liquid crystal display has high transmittance, good color shift and display quality, so the negative liquid crystal is used in the main liquid crystal display, such as IPS and FFS modes. Nevertheless, for the physical characteristic of negative liquid crystal itself, the image sticking (IS) is more serious than positive crystal liquid, especially the area nearby the IC bonding. In order to improve the afterimage, we measured the different data, such as the temperature and common voltage (Vcom) of the serious and slight area in the sample cell, and we found that the Vcom voltage has different shift in the serious and slight area. The influence factors of IS were analyzed, and improvement method was proposed and it is effective to reduce the image sticking.关键词：negative liquid crystal;image sticking(IS);common voltage
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发布时间：2020-08-12 - 摘要：The high birefringence liquid crystals have important applications in LCD, but they are instable under UV exposure due to the conjugated unsaturated structures. The ultraviolet stability of high birefringence liquid crystals was studied in this paper. First, several different additives were added to the liquid crystal mixture A, such as triphenylphosphine oxide,4'-propylbi(cyclohexane)-4-formaldehyde, 4-propyl-4'-cyclopentyl-3,5-difluorobiphenyl and UV-P. The liquid crystal mixtures were poured into TN-7.0-R test cells after stirred uniformly, then the test cells were exposed to ultraviolet, finally the liquid crystal parameters were tested. The results show that the UV stability of liquid crystal A can be significantly improved by UV-P,because the UV absorption of UV-P is most similar with liquid crystal A.关键词：high birefringence;liquid crystals;ultraviolet stability;UV-P
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发布时间：2020-08-12
Material Physics & Chemistry
- 摘要：Oncell touch panel technology is a new technology of touch panel which touch sensor is integrated on the surface of LCD.Compared with outcell touch panel,oncell touch panel is thinner,lighter and easier to produce.New technology, such as single layer multi-touch capacitor touch panel,PMMA+PC cover, AR,AF film and optical bonding etc. are used in Oncell touch panel. Oncell touch panel can match different LCD driving method.Oncell touch panel can run regularly in rugged environment such as complex electromagnetic environment,strong sunlight,high and low temperature.Finally,the new technology of Oncell touch panel can support up than 3 point touch,glove touch and head impacted test.The surface reflectance is lower than 3%, and linearity is ±1.5 mm.The Oncell touch panel solved the key technical problems and can pass the automotive test.Thus Oncell touch technology will be the most important technology of automotive.关键词：Oncell;automotive;touch technology;all joint;head impact;CTP
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发布时间：2020-08-12 - 摘要：In liquid crystal display, the uniformity of spacers influences contrast degree and color tone change, et al. Thus, the test method of uniformity of spacers in LCD is researched in this paper. Firstly, the liquid crystal cells are made by using dry spray method and wet spray method, then the distribution character of spacers is studied by using the polarizing microscope. It is found that, in normal case, the least distance of spacers in LCD is close to 20 μm and the largest distance exceeds 100 μm. The cluster of spacers is the main defect which leads to badly distribute. Under laboratory conditions, the cluster of spacers is more serious by using dry spray method but this phenomenon doesn't exist basically by using wet spray method. Therefore, by using the way of polarization interference and through adjusting the relative angle of up and down polarized plates of the polarizing microscope, the spacers and distribution of spacers can be directly observed without destroying the LCD. The principle of the spacers uniformity tested by using polarization interference is also analyzed.关键词：spacer;uniformity;polarization interference;liquid crystal cell
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发布时间：2020-08-12 - 摘要：Low Correlated Color Temperature (CCT) light sources are preferred for physiologically-friendly illumination due to their low suppression of melatonin secretion, and high power efficiency is important in energy-saving applications, too. We fabricated low-CCT white organic light-emitting diodes (WOLEDs) from three and four basic phosphors by spin coating method using a single emission layer. The best device fabricated shows a CT less than 2 500 K and CRI of 83 in a brightness of about 100-10 000 cd/m2. Moreover, these devices exhibit a current efficiency of 13.4 cd/A at 100 cd/m2 or 17.8 cd/A at 1 000 cd/m2, which is comparable with incandescent bulbs. The high performance, solution processable and physiologically-friendly OLED can be an ideal candidate for a light source designed to safeguard human health, especially at night.关键词：white light illumination;low color temperature;OLED;solution process;phosphorescence
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发布时间：2020-08-12 - 摘要：Based on soluble polymeric thin-film transistor, the characteristics of organic thin-film transistors (OTFTs) with various fabrication processing conditions were compared. The results demonstrated that the characteristic of OTFTs isn't almost influenced by spin-coating with air or N2 atmosphere, yet it is seriously influenced by annealing with air or N2 atmosphere. From the point of field-effect mobility, it demonstrated that the mobility of OTFT devices with annealing in N2 atmosphere is more than two times as much as that with annealing in air, when the annealing temperature is the range from 100 ℃ to 190 ℃.关键词：polymer;organic thin-film transistor;field-effect mobility
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发布时间：2020-08-12 - 摘要：In order to optimize via hole design of TFT array substrate and reduce via hole contact resistance, the contact resistance of different size, shape, number of Mo/Al/Mo and Indium-Tin Oxide (ITO) connection via holes are tested by Kelvin Four-terminal sensing. Then via hole morphology is characterized by scanning electron microscopy (SEM),focused ion beam (FIB) and energy dispersive spectroscopy (EDS). Finally, the mechanism of via hole contact resistance test results are analyzed. Experimental results indicate that the bigger via hole area is, the smaller the contact resistance will be, and in the same via hole area, the contact resistance of rectangular via hole is smaller than that of a square via hole, the contact resistance of the multi small holes is smaller than that of the single big via hole, the via hole contact resistance of Gate metal and ITO is smaller than that of SD metal and ITO. For reducing via hole contact resistance, via hole area is maximized. The rectangular via hole is better than that of the square via hole, the multi small holes are better than that of the single big via hole, and via etch process is optimized to reduce top Mo loss.关键词：thin film transistor array process;contact resistance;via hole design optimization
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发布时间：2020-08-12 - 摘要：In order to analyse the effect of different outcouping layers on optical and electrical properties of top-emitting organic white light emitting devices, in experiment, the transmittance and loss (absorption and reflection) of ETL/EIL/Mg:Ag/matching layers were numerically calculated. At the same time, some top organic white light emitting devices with common cathode configurations were fabricated, and the optical and electrical properties of OLED devices prepared with different refractive index matching layers were analyzed.The experimental results showed that there were biggish difference in optical transmittance and loss of ETL/EIL/Mg:Ag/matching layers with same thickness LiF and Al2O3. At the current density of 20 mA/cm2, according to the change of viewing angle from 0° to 60°, the electroluminescence emission spectra of OLED devices prepared with dual index matching layers occured to blue shift, but throughout the viewing angle from 0° to 60°, the color coordination always stayed close to 0.33,which indicated that the color coordinates of top-emitting white light devices can be adjusted by different refractive index matching layer to achieve white light emission at large viewing angle.关键词：organic white light emitting devices;top-emitting;transfer matrix;outcoupling layer
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发布时间：2020-08-12
Device Physics & Device Technology
- 摘要：In order to control the TFT-LCD, a design method of TFT-LCD controller is introduced, with the STM32 and the CPLD as the core controller, along with an external SRAM as the display cache. Firstly, the overall architecture of the design is analyzed. The communication protocol between STM32 and CPLD is drawn up inside of STM32. The drive of LCD timing, the parsing of communication protocol and the reading and writing of the SRAM are implemented by the CPLD. At last, the LCD timing and the reading and writing of the SRAM are simulated, and the figure of the actual operation effects are shown. The results indicate that the TFT-LCD can show the picture and word correctly controlled by the proposed design method. The method is of simple structure, high cost performance and higher application value.
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发布时间：2020-08-12 - 摘要：According to the character of LED variable message sign which requires high reliability, high stability and less maintenance, in this paper, the whole LED variable message sign is divided into multiple sub areas, and ZigBee wireless network is applied in each sub-area to realize distributed control. Each sub-area becomes a ZigBee node which is controlled by CC2530 to complete display, communication, sensing and so on. The hardware design for every node is the same, which consists of high frequency core board and low frequency base board. Master control module communicates with remote control center, generates dot matrix display data for each sub-area and transmits these display data to coordinator. User program which is based on event process of multitask architecture is designed by employing Z-stack protocol. The user program includes point to point communication, broadcast communication and serial communication that is based on finite state machine. Structure of high frequency core board and low frequency base board is beneficial to lower manufacture cost of print circuit board and improve universality and interchangeability. This design enhances reliability and stability, avoids fault spread, reduces maintenance frequency, allocates total data throughout to multiple CPUs, makes the whole system become a multi-core processor.关键词：ZigBee wireless network;distributed system;core board and base board;point to point communication;broadcast communication;variable message sign
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发布时间：2020-08-12 - 摘要：In order to realize the real-time video image geometric calibration in large field of view image applications, especially in large format projection mosaic technique field, this paper analyzes the video image geometric calibration and its realization based on FPGA. First, according to the basic theory of image geometric calibration, this paper describes the simulation of algorithms with Matlab and other tools, and designs the basic frame of the video image geometric calibration system. Then, the system structure is detailed designed based on the hardware resources of DE2 platform and the geometric calibration module is simulated. Finally, based on the actual calibration test, this paper concludes that the experimental results achieve the desired target of real-time video image geometric calibration. Experimental results show that the image which has been calibrated and projected by projector is consistent with the simulation results. The delay of system is less than 10 clock cycles, far less than millisecond level, and the value of delay time is a constant. The inaccuracy of the calibration system is no more than one pixel. This design achieves the desired target of real-time video geometric calibration, which has considerable significance for reference.关键词：large field of view;projection mosaic technique;geometric calibration;FPGA
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发布时间：2020-08-12 - 摘要：In order to meet the requirement of the market for LCD panel's high resolution and narrow frame performance, the gate driver in array(GIA) employing a_Si:H TFTs technology has emerged in recent years. This paper briefly introduced the operation principle of the traditional integrated gate driver and its effects on LCD panel design, then proposed a novel gate driving circuit through single gate to control rows of pixels, so that the number of gate lines can be sharply decreased which result in saving much more space for narrow bezel design. Simulation results show that a little noise with 2.5 V happens at off-state of the new circuit's gate line, and the delay time of the gate waveform at both the rising and falling edge is only 3.5 μs, totally. The charging and discharging of pixel can achieve for normal display. At the same time, the new driving circuit proposed in this paper can greatly reduce frame border of panel, through the way of reducing the number of gate fanout lines.关键词：LCD panel;gate driver;high resolution;narrow border
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发布时间：2020-08-12 - 摘要：Infrared touch screen works through light emitting diode transmitting infrared light and infrared receiver diode receiving infrared light, so the sunlight will have interference to it. Scanning period of anti-light infrared touch screens which use serial scanning mode is too long. Eight kinds of crystal ——30.072 kHz, 36 kHz, 38 kHz, 38.4 kHz, 40 kHz, 48 kHz, 50 kHz, 51.2 kHz are used to design signal sources of infrared emission diodes. Then, the same frequency crystals are used to design frequency selective circuits. The design make eight scanning units working simultaneously come true. It enhances the anti-light ability of IR touch screen and solves the problem of interference among the eight infrared transmitting diode in parallel scanning mode, reducing scan cycle.关键词：infrared touch screen;anti-light interference;parallel scanning;frequency selective circuits;crystal
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发布时间：2020-08-12
Driving & Controlling
- 摘要：In order to realize multi-regions moving object detection in video surveillance, the shortage of traditional moving object detection algorithm is analyzed. Combining the background subtraction algorithm and frame difference algorithm, we propose a method which dynamically refresh the background. This algorithm can adapt with the background automatically, and reduce error detections caused by the change of background. We build a video surveillance system based on a FPGA chip, and implement the algorithm on the chip. The system can detect moving object in a 640 pixel×480 pixel, 30 frames/s video stream. The system also provides a function which detects moving object in independent regions. The number, size and location of the regions can be set easily by simple keystrokes. The system's configuration is convenient, and has strong flexibility. It can be utilized in various fields such as intelligent surveillance and production safety.关键词：video surveillance;moving detection;background dynamic refresh;FPGA
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发布时间：2020-08-12 - 摘要：In order to satisfy the requests of the high frame rate and high resolution of fast moving scene in national defense, research and industry, a camera with high-speed and high resolution was developed. The functions and characteristics of CMOS image sensor AM41V4 which can cover the requests were introduced, a camera system based on the image sensor was designed. The FPGA was used as the core to control the system timing and DDR solid storage was embedded as the imaging memory in the camera system. Consequently, a flexible working pattern according to specific requirements of the test shoot occasions was realized. The frame rate of the system is 1 000 frames per second, when the resolution of the image is 1 920 pixel×1 080 pixel. Besides, the camera system reaches a real-time monitoring function. The system has the advantages of high shooting speed, clear image, high performance and flexibility. It has great value for fast capture and shooting record of high-speed moving targets.关键词：CMOS image sensor;high frame rate;high resolution;FPGA;fiber channel;SFP+
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发布时间：2020-08-12 - 摘要：According to the characteristic of image enhancement, quantum immune frog leap algorithm is proposed. Frog individuals were quantum-encoded by this algorithm according to the order of fitness degree, meanwhile, the leap frog movements were discretized. Through the dynamic adjustment of the revolving gate of quantum leapfrog, all quantum bits of the quantum chromosome were deflected towards the dynamic optimization of the ground state of quantum bits which were corresponded to the optimal solution. Qubits were mutated by adopting Hadamard gate, the leap frog immunization was pixel-matched based on the feminine selection algorithm, and image enhancement process was provided. The experimental result show that effect of outline and details of QILF is more clearly, the better SSIM is 0.984 9.关键词：quantum immune;negative selection;enhancement
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发布时间：2020-08-12 - 摘要：To increase the airborne photoelectric reconnaissance devices' field of view,most aerial cameras adopt the method of scanning to photograph the earth. For the purpose of image distortion caused by the oblique photography of array CCD aerial camera, a practical auto-rectification approach was proposed in the thesis.As there was a dual-axis rotation (specifically,the azimuth and pitch motion) between these array CCD aerial cameras and aircrafts, this paper introduced a new approach for image geometric correction that took into account both the rotational angles from cameras to aircrafts and the attitude angles of the aircrafts relative to the ground. First, the six attitude angles projective rectification model of these array CCD aerial cameras was established. Then, the relationship of pixel coordinates between distortion image and standard image was obtained. Through coordinate transformation and luminance bilinear interpolation, the aerial remote sensing image with distortion was auto-accurately rectificated. Finally, the aerial image of an airport was corrected using the six attitude angles projective rectification model, the ground control point based multinomial correction model and the correction method of matching the distortion image and reference image, respectively. Experiments show that the six attitude angles projective rectification model can achieve pixel level correction precision. For 512 pixel×512 pixel images,the root mean square error of image correction can reach 1.174 7 pixel accuracy when the accuracy of attitude angles is 3 min.The proposed algorithm in the thesis doesn't need for reference images and ground control points, and facilitates engineering application. It can satisfy the system requirements of online, real time, higher precision and stabilization.关键词：aerial remote sensing;array CCD images;geometric correction;oblique photography
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发布时间：2020-08-12 - 摘要：The miniature cameras are the critical equipments to support the low-cost Micro Air Vehicles or small satellites for earth observation and many other applications. So a miniature imaging system with high resolution and large area array was proposed in this paper. Firstly, the target sampling distance and swath width were estimated for the designed imaging system. Then the electronic scheme of the system was described, where the working principle of the key chip OV14825 was introduced, and the software design based on FPGA was analyzed for serial differential data receiving and forwarding. Finally, imaging experiments were carried on the designed camera. The resolution was better than 0.5 mm when imaging in the 13 m distance, and the obtained images were rich in details, which proved that the scheme was feasible. And the miniature cameras with high resolution and large area array were of great value.关键词：miniature camera;CMOS image sensor;area array;resolution
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发布时间：2020-08-12 - 摘要：Forward motion compensation (FMC) system for airborne area mapping camera is designed, and the working schedule is presented. The FMC system uses piezoceramic actuator to drive the focal plane module directly. The piezoceramic actuator works at position close loop mode whose given position is set incrementally. This makes focal plane module move at desired speed so that forward motion speed can be compensated. Experiments imply that the maximum FMC residual error of the FMC system is 0.38 μm when the forward motion velocity is 2.5 mm/s and the maximum residual FMC error is 0.48 μm when the forward motion velocity is 3.5 mm/s. The residual errors are far less than one third of the pitch dimension. The FMC frequency is 25 Hz which satisfies the demand of high frequency aerial FMC while the maximum exposure time is 20 ms.关键词：forward motion compensation;piezoceramic;aerial imaging
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发布时间：2020-08-12
Imaging Technology & Image Processing
- 摘要：In order to accurately obtain the life information of LED lamps in a short time, three-parameter Weibull function was applied to describing the life distribution based on three groups of constant-stress accelerated life test data. The processing and analysis on test data was achieved by Bilinear Regression Method (BRM), and the self-developed life prediction software was employed to precisely calculate the life of LED lamps under normal working stress. The numerical results show that the LED lamps life submits to three-parameter Weibull distribution, and the accelerated model meets the Arrhenius equation. The LED lamps' life predicted precisely can provide technical references for engineering technicians with regard to the product's reliability design.关键词：Weibull function;Arrhenius equation;BRM;LED lamps;life prediction
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发布时间：2020-08-12 - 摘要：The degree of motion blur is one of the important indices for the display quality of LCD. At present, the human vision detecting method is mostly used in domestic area of LCD moving picture display performance detection. But, the result of human vision detection is obviously affected by the subjective judgment of the inspectors, and easily interfered by the external environment and self-mental factors, which is not conducive to the unification and standardization of production. Referring to the idea of image quality assessment (IQA), a new LCD motion blur detecting method is proposed in this paper based on Regional Contrastand Structural Similarity (RCSSIM) algorithm. Using the static image as reference, the definition metric of LCD motion blurred image can be obtained by evaluating the quality of it acquired on LCD to indicate the performance of LCD moving picture displaying.The results of the simulations and actual experiments show that the proposed detecting metric can not only quantify the LCD's motion blur degree well, but also match the human's subjective perception.关键词：LCD;motion blur;image quality assessment;regional contrast structural similarity
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发布时间：2020-08-12 - 摘要：Based on the PVA mode, this paper researches a new technology of viewing angle controllable LCD. By increasing the pretilt angle of liquid crystal molecular at dark states, it realizes a high contrast with low dark luminance at wide-viewing angle(WVA) mode and low contrast with high dark luminance at narrow-viewing angle(NVA) mode. By burning different code to Tcon ROM, according to the demand of users to realize WVA or NVA at different conditions, it gets two types of source voltages. The simulation results show that the up/down/left/right view angle are more than 8°at WVA and less than 40° at NVA, the results show that the new viewing angle controllable technology is effective.关键词：view angle controllable;contrast;PVA mode
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发布时间：2020-08-12
Measurement Technology
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