Split bregman method-based background extraction for blob-mura defect detection in thin film transistor-liquid crystal display image

In this paper, we present the results of using a split Bregman method for blob-Mura defect detection in a thin-film transistor-liquid crystal display (TFT-LCD) image. A reference image obtained by the split Bregman method was simply subtracted from a test image to detect blob-Mura defects. For a test image, two resulting images containing black or white bob-Mura defects were obtained separately. Through simulation it was verified that the proposed method has a superior capability for detecting blob-Mura defects.     

Application of piecewise linear regression twice to inspect the defective regions on thin film transistor liquid crystal display panels

Detecting defects in thin film transistor liquid crystal display (TFT-LCD) panels can be difficult due to non-uniform background brightness and slightly different brightness levels between the defective regions and the background. One well-known method is to inspect the defects of TFT-LCD panels using the polynomial approximation method. However, there are some problems such as determination of the polynomial degree and ghost objects. In this paper, to overcome these problems, we propose a new algorithm using the piecewise linear regression twice and Niblack’s method which do not require to determine the polynomial degree for the approximation. Our algorithm effectively removed ghost objects. The experimental results show that our proposed method performed well and was good enough to substitute the polynomial approximation method.     

The fabrication and optical detection of a vertical structure organic thin film transistor

Using vacuum evaporation and sputtering process, we prepared a photoelectric transistor with the vertical structure of Cu/copper phthalocyanine (CuPc)/Al/copper phthalocyanine (CuPc)/ITO. The material of CuPc semiconductor has good photosensitive properties. Excitons will be generated after the optical signal irradiation in semiconductor material, and then transformed into photocurrent under the built-in electric field formed by the Schottky contact, as the organic transistor drive current makes the output current enlarged. The results show that the I–V characteristics of transistor are unsaturated. When device was irradiated by full band (white) light, its working current significantly increased. In full band white light, when V_ec = 3 V, the ratio of light and no light current was ranged for 2.9–6.4 times. Device in the absence of light current amplification coefficient is 16.5, and white light amplification coefficient is 98.65.     

Leakage of light in liquid crystal displays and birefringent thin film compensators

This paper elucidates the physical origin of leakage of light in the dark state of liquid crystal displays (LCDs) and describes birefringent thin film compensators to mitigate the problems. There are two fundamental sources of leakage of light in LCDs. They are the leakage of light through a pair of ideal crossed polarizers, and the leakage of light due to elliptical state of polarization after transmitting through the liquid crystal (LC) cell. The leakage of light in the dark state leads to poor contrast ratios and color instability, particularly at large viewing angles. The paper then describes the employment of sixth-wave (λ/6) plates as well as various wave plates that function as birefringent compensators for eliminating the leakage of light in LCDs.     

Modeling and computer design of liquid crystal display backlight with light polarization film

The article is devoted to elaboration of the model of scattering polarization film like dual brightness enhancement film (DBEF). This model is used for computer design of backlighting system of liquid crystal display (LCD) where light polarization is important. The model elaboration required development of measurement methods and reconstruction of the parameters for the film polarization, development of the accurate computer model of the polarized light scattering on thin surface. The results of design of LCD backlight with polarization film are presented in the article as well. So it was demonstrated that design of backlight devices with DBEF is possible with help of elaborated software.     

Experimental investigation of one-sided optical transparency in cholesteric liquid crystal thin film

Influence of boundary conditions on optical properties of a layer of cholesteric liquid crystal (CLC) has been investigated. In particular, a sample was obtained which is transparent for circularly polarized light incident from one side and gives losses in the transmission spectrum (within nearly 100 nm wide wavelength range) if light is incident from the opposite side, i.e. exhibits optical diode behavior. Two selective reflection bands were detected in the reflection spectrum of the sample. Spectral position of both selective reflection bands and transmission spectrum are shown to be CLC temperature-controllable.     

Nematic liquid crystal around a spherical particle: Investigation of the defect structure and its stability using adaptive mesh refinement

We investigate the orientation profile and the structure of topological defects of a nematic liquid crystal around a spherical particle using an adaptive mesh refinement scheme developed by us previously. The previous work [J. Fukuda et al., Phys. Rev. E 65, 041709 (2002)] was devoted to the investigation of the fine structure of a hyperbolic hedgehog defect that the particle accompanies and in this paper we present the equilibrium profile of the Saturn ring configuration. The radius of the Saturn ring r_d in units of the particle radius R₀ increases weakly with the increase of , the ratio of the nematic coherence length to R₀. Next we discuss the energetic stability of a hedgehog and a Saturn ring. The use of adaptive mesh refinement scheme together with a tensor orientational order parameter allows us to calculate the elastic energy of a nematic liquid crystal without any assumption of the structure and the energy of the defect core as in the previous similar studies. The reduced free energy of a nematic liquid crystal, , with L₁ being the elastic constant, is almost independent of in the hedgehog configuration, while it shows a logarithmic dependence in the Saturn ring configuration. This result clearly indicates that the energetic stability of a hedgehog to a Saturn ring for a large particle is definitely attributed to the large defect energy of the Saturn ring with a large radius.Received: 10 December 2003, Published online: 2 March 2004PACS: 61.30.Cz Molecular and microscopic models and theories of liquid crystal structure - 61.30.Jf Defects in liquid crystals - 82.20.Wt Computational modeling; simulation     

Large eddy simulation of turbulent premixed combustion using tabulated detailed chemistry and presumed probability density function

A method of chemistry tabulation combined with presumed probability density function (PDF) is applied to simulate piloted premixed jet burner flames with high Karlovitz number using large eddy simulation. Thermo-chemistry states are tabulated by the combination of auto-ignition and extended auto-ignition model. To evaluate the predictive capability of the proposed tabulation method to represent the thermo-chemistry states under the condition of different fresh gases temperature, a-priori study is conducted by performing idealised transient one-dimensional premixed flame simulations. Presumed PDF is used to involve the interaction of turbulence and flame with beta PDF to model the reaction progress variable distribution. Two presumed PDF models, Dirichlet distribution and independent beta distribution, respectively, are applied for representing the interaction between two mixture fractions that are associated with three inlet streams. Comparisons of statistical results show that two presumed PDF models for the two mixture fractions are both capable of predicting temperature and major species profiles, however, they are shown to have a significant effect on the predictions for intermediate species. An analysis of the thermo-chemical state-space representation of the sub-grid scale (SGS) combustion model is performed by comparing correlations between the carbon monoxide mass fraction and temperature. The SGS combustion model based on the proposed chemistry tabulation can reasonably capture the peak value and change trend of intermediate species. Aspects regarding model extensions to adequately predict the peak location of intermediate species are discussed.     

Localized bifurcations and defect instabilities in the convection of a nematic liquid crystal

The stationary and the time-dependent homogeneous ordered states in convection may both become unstable against localized perturbations. Defects are then created and they may contribute to the disorganization of the homogeneous state. We present an experimental study of defects in some homogeneous stationary structures as well as in the traveling-wave states of convection of a nematic liquid crystal. We show that the core of the defects is a germ of the unstable state and it can become unstable under the external stress. Then, either fully homogeneous states with the symmetry of the core, or complex disordered states can develop from the local instability of defects in processes quite similar to displacive transitions in solids. Some of the main features are qualitatively similar to numerical simulations of an appropriate Landau-Ginzburg equation.     

透反区响应时间相等的双盒厚透反液晶显示器

提出了一种透反区响应时间相等的双盒厚透反液晶显示器。该透反液晶显示器在透射区采用了强锚定能边界条件,以缩短其响应时间;在反射区采用了弱锚定能边界条件,以增加其响应时间;采用过压驱动技术,使透反区的响应时间相等。分析了该透反液晶显示器的结构和原理,设计了透射区和反射区的边界锚定能,计算了响应时间和电光特性,得到了透反区响应时间相等,且具有良好电光特性的双盒厚透反液晶显示器。     

3d电子在立方晶场中的能级和波函数及概率密度图

应用简并微扰论计算了一个3d态的氢原子处于立方晶场中的能级和波函数,并用数学软件Matlab精确地图示了3d电子在立方晶场中的概率密度．     

Superheating in liquid and solid phases during femtosecond-laser pulse interaction with thin metal film

Superheating of the liquid phase caused by non-equilibrium evaporation during femtosecond-laser processing of a thin metal film is investigated by adopting the wave hypothesis along with the two-temperature model. The simulation results show that the superheating in the liquid occurs shortly after the evaporation. For a 100-fs laser pulse of 0.7 J/cm², the maximum degree of superheating in liquid can reach 600 K. The superheating in solid can also be captured in the current model, which can be as high as 300 K. The effects of laser fluence, pulse duration and film thickness on the degree of superheating were studied. A higher laser fluence will increase the degree of superheating in liquid significantly but has little effect for the solid part. In the range adopted in the current work, the pulse duration has little effect on the degree of superheating in both liquid and solid phases.     

Intentionally incorporated defect and its consequences in oxide thin film through Radio Frequency Magnetron Sputtering Technique

Radio Frequency Magnetron Sputtering Technique has been employed to prepare metal oxide thin film of ZnO and CdO. The films were deposited in such condition that some point defects like oxygen vacancies have been intentionally incorporated. The defects appeared with significant modification in the properties of the thin films. The prepared films were characterized by studying with X-ray diffraction study, X-ray photoelectron spectroscopic measurement, optical transmittance measurement, and electrical study. The electrical properties are found to change profoundly with the defect concentration. Consequently the optical properties also have been changed.     

Structures and phase transitions in thin free standing films of an antiferroelectric liquid crystal

The premises of a discrete mean-field model for polar smectic liquid crystals are tested by analyzing the ellipsometric experiments on two, three, and four-layer freestanding films of MHPOBC. The measured temperature dependences of the ellipsometric parameters in a weak dc external field are compared to the predictions of a simple clock model. A very good quantitative agreement is found indicating an odd-even effect: XY structures are stable for odd and Ising-like structures for an even number of layers.     

Spectroscopic ellipsometry study of liquid crystal and polymeric thin films in visible and near infrared

In this work, we propose spectroscopic ellipsometry as a suitable method for measuring optical properties in soft materials, polymers and liquid crystals, specially selected for use in photonics applications. We show the results of our measurements on some multilayered samples, in the range from visible to the near-IR region, of interest for telecom applications. We point out potentialities and limits of the technique and compare the obtained results with another experimental method, the m-lines spectroscopy, and/or with existing data in the literature. The results about the optical parameters for the analysed materials (the nematic liquid crystal 5CB, one commercial and one lab made optical polymer, and an Indium Tin Oxide film) are useful and interesting by themselves. In fact, as a paradigmatic example, we briefly discuss how an incomplete knowledge of this kind of data can lead to a wrong design of a Bragg grating device. However, more than in the provided data, we put the interest of the present analysis in the warnings about spectroscopic ellipsometry utilization and eventually the necessity of getting complementary information.Received: 13 May 2004, Published online: 29 June 2004PACS: 78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity) - 78.66.Qn Polymers; organic compounds - 07.60.Fs Polarimeters and ellipsometers     

Director configuration and dynamics of a nematic liquid crystal around a two-dimensional spherical particle: Numerical analysis using adaptive grids

We study numerically the director and orientational order parameter configurations in a nematic liquid crystal around a two-dimensional spherical particle on the basis of the tensor order parameter formalism. To properly account for the large length scale difference between the particle and the accompanying orientational defect, we devise an adaptive grid scheme in which the lattice spacing is automatically and locally adjusted in response to the spatial gradient of the orientational order parameter. This adaptive grid scheme is useful in studying dynamical as well as static orientational structures. We present a simulation result which shows how a hedgehog defect of topological charge -1 becomes unstable in two dimensions, and splits into a defect pair of topological charge -1/2, located symmetrically around the particle. Received 14 September 2000 and Received in final form 27 December 2000     

Injection of holes and their localization in defect states at the interface between an electrochromically sensitive single crystal and an amorphous thin film of a complex tungsten oxide

The dynamic current-voltage and estance-voltage characteristics of amorphous thin films of complex tungsten oxides (tungsten oxide bronzes) and, for comparison, tungsten oxide bronze single crystals have been measured with a change in the character of their interaction with electromagnetic radiation. The optoelectronic properties of the samples have been analyzed taking into account the important role of the processes of hole injection, carrier localization in traps, and nanostructurization. A model of the physical processes occurring in the surface and near-surface regions at the interface between a tungsten oxide bronze and a liquid proton electrolyte, different from the generally accepted approach, is considered.     

Surface morphology characterization of pentacene thin film and its substrate with under-layers by power spectral density using fast Fourier transform algorithms

Surface morphology of pentacene thin films and their substrates with under-layers is characterized by using atomic force microscopy (AFM). The power values of power spectral density (PSD) for the AFM digital data were determined by the fast Fourier transform (FFT) algorithms instead of the root-mean-square (rms) and peak-to-valley value. The PSD plots of pentacene films on glass substrate are successfully approximated by the k-correlation model. The pentacene film growth is interpreted the intermediation of the bulk and surface diffusion by parameter C of k-correlation model. The PSD plots of pentacene film on Au under-layer is approximated by using the linear continuum model (LCM) instead of the combination model of the k-correlation model and Gaussian function. The PSD plots of SiO₂ layer on Au under-layer as a gate insulator on a gate electrode of organic thin film transistors (OTFTs) have three power values of PSD. It is interpreted that the specific three PSD power values are caused by the planarization of the smooth SiO₂ layer to rough Au under-layer.