Abstract: A series of azobenzene containing group Poly (L-lactic acid) (PLLA) were synthesized by Ring-Opening Polymerization of L-lactide (L-LA) catalysted by Sn (Oct)2 initiated by alcohol-OH containing the azobenzene chromophores. Their molecular weights were well controlled by the feed ratio as characterized by Gel Permeation Chromatography (GPC) and 1H NMR Spectrometry and agreed well with theoretical values. The thermal properties and liquid crystal phases were investigated by Differential Scanning Calorimetry (DSC), polarized optical microscopy (POM) and X-ray Diffraction (XRS) measurements. Cis-trans photoisomerization behavior of the polymers in the solutions and the films were studied with UV irradiation. By the Circular Dichroism Spectroscopy (CD) characterization of the solutions and films of the polymer, the PLLA segments show huge optical rotation power in helical structure.
Abstract: Two HBC derivatives (HBC-C13 and HBC-C15), both containing 6 odd-carbon alkyl chains surrounding the rigid plane core, were investigated as discotic liquid crystal. The difference between their thermal behaviors has been investigated by using differential scanning calorimetry (DSC). Their mesomorphic phase behavior was observed by polarizing optical microscopy (POM). A remarkable odd-even effect in the phase transition temperatures was observed for all HBC derivatives (HBC-C12, HBC-C13, HBC-C14, HBC-C15 and HBC-C16).
Abstract: In this study, a triphenylene-based discotic liquid crystal 3,6-dicarbethoxy-2,7,10,11-tetra-pentyloxytriphenylene was synthesized. The chemical structure was characterized by FTIR, 1HNMR.The mesophases of the material synthesized here was characterized by using polarizing optical microscopy (POM), differential scanning calorimetry (DSC). It was found that the compound displayed columnar phase during cooling at 164.7 °C and the columnar phase can be preserved even at room temperature. The charge transportation properties of the compound were measured by using time-of-flight method.
Abstract: A new type of able liquid crystalline polymer with a coumarin-containing mesogenic side group that could be photo-crosslinked was synthesized in this paper. The structure of the intermediates, monomers and polymers were characterized with FTIR and 1HNMR measurement. DSC, TG, and hot stage polarized optical microscopy were employed to study the phase transition temperature, mesophase texture, and thermal stability of the liquid crystalline polymers. The results indicated that both the monomer and polymer exhibited liquid-crystalline features over a wide temperature range.
Abstract: A transflective dual-mode liquid crystal display (LCD) featuring single-cell-gap structure has been proposed in this paper. Unlike transflective single-mode LCDs, dual-mode LCD can work as either monostable transmissive or bistable reflective LCDs in a sense that two different modes of display are unified in one device. We have confirmed that it has not only desirable electro-optical performance but also longtime memory ability.
Abstract: Different from common commercial liquid crystal displays (LCDs), LCDs in military applications have some special requirements including high luminance, wide operating temperature, and night vision compatibility. This paper designs a direct-lit LED backlight for a 5 in×5 in LCDs and puts forward three solutions for heat dissipation. The simulation results show that the solution of 17×17 LED array on common opening FR4 PCB can satisfy the requirement.
Abstract: The inspection of the defects in LED chip has become a critical task for manufacturers in order to enhance product quality. In this paper, a new approach for the defect inspection of LED chip is presented, which uses both the features of defects and the generalized regression neural networks. The approach consists of following three steps. First of all, preprocess of LED chip image is performed by using the image operations such as image enhancement. Secondly, the chip image is divided into a lot of sub-regions, the features of each sub-region are extracted, the database of features is built. Thirdly, an initial structure of generalized regression neural network is constructed, then the neural network is trained by using the features in database. The generalized regression neural network has the ability to converge to the underlying function of the data with only few training samples available, and the additional knowledge needed to input by the user is relatively small. The experimental results show that the defect inspection approach in this paper can effectively identify the LED chips with defects.
Abstract: A method using a TN-LC cell as the mask to create individual bidirectional alignment layer in a single photoalignment exposure was demonstrated. Both the theory and experiments were investigated. The results indicated that the bidirectional alignment layer can be achieved rapidly and individually. The method exhibited significant potential in special LCD production and security applications.
Abstract: In order to improve the classification accuracy of cell subsets, a telecentric system which is based on the characteristics of cell’s scattering is designed. The irradiating and receiving light work collinearly in this system, and the optical receiving efficiency of back scatter light increases to twice the origin by using a special mirror. The optical design parameters and structures are given by using aberration theories and optical design software. The performance and signal collection of the optical system are analysised. When the resolution is 100lp/mm, the MTF is more than 0.17. The stray light is effectively filtered out and the accuracy of scattering signal is improved. The optical system can be used to identify eukocyte.
Abstract: This paper describes a backlight system that can not only reach high luminance but perform a wide color gamut with NVIS compatibility. The backlight consists of red (R), green (G), blue (B), and amber (A) four colors LEDs. During daytimes, RGBA LEDs are simultaneously turned on, providing more luminance and wider color gamut. When working in the night mode, the red LEDs are turned off. The simulation and practical results show that RGBA backlight present the characteristics of high luminance and wide color gamut with compatibility of night vision.