Solid State Phenomena Vols. 181-182

Abstract: The circuits should be tested extensively during the production process, the power consumption in a circuit during test mode can be higher than that the consumption during normal operation mode. The circuits are usually designed for normal operation mode, which makes it important to consider power consumption during test mode, otherwise the higher power consumption during test mode may cause the circuits being damaged. In this paper, a new approach for the test pattern design of VLSI circuits is presented, the approach defines the weight values of primary inputs of circuits, makes use of both circuit structure information and pseudorandom test generation to produce the test patterns, such that the circuit has lower power consumption when the test patterns are applied to the circuit primary inputs. The experimental results show the approach in this paper can get significant power consumption reduction compared with conventional random test algorithm.

Abstract: The progress in digital high resolution, small pixel liquid crystal on silicon (LCOS) microdisplays will be discussed and how it will lead to HD displays in very small form factors. The first generation of this technology is enabling very small yet high resolution projection engines devices that can be embedded in cell phones, cameras, head-mount displays, and set-top boxes and the next generation will bring HD resolution. As lasers become more affordable we see this LCOS display technology fundamentally changing the power consumption, cost, and size of pico-projectors and other display devices. One of the most interesting conclusions is that by using LCOS technology in combination with lasers, it should soon be possible to build an “ultra-green” television that would consume less than 1/8th the power of equivalent size LCD flat panel TV.

Abstract: For the purpose of developing novel electrochromic materials, star-shaped oligothiophene derivatives with phenyl core, 1,3,5-tris (2′-thienyl) benzene (3TB) and 1,3,5-tris (5′-(2,2′- bithienyl)) benzene (3BTTB) were synthesized, and their electrochromic properties were investigated. It was found that 3TB and 3BTTB as solid films showed reversible, clear color changes on electrochemical doping and dedoping. The two oligothiophene derivatives with phenyl core constitute a new class of potential electrochromic materials.

Abstract: The paper proposes a global backlight dimming algorithm for CR enhancement and power reduction. S-shaped function is involved to help improve CR. Both the backlight dimming level and the turning point grayscale of the s-shaped curve are determined by the histogram of the input image. The pixels with the grayscales more than the turning point are compensated to become brighter and the pixels less than turning point become darker. The simulation results show that the proposed dimming algorithm can improve CR by average 34.95% and reduce power consumption by 11.30%.

Abstract: Soluble polypyrrole was obtained by naturally oxidizing pyrrole in air at room temperature for one to four years. Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy and ultraviolet-visible absorption spectroscopy were employed to characterize the chemical structures of the naturally oxidized polypyrrole. The electroluminescence from the naturally oxidized polypyrrole was recorded. The electroluminescence of the naturally oxidized polypyrrole was broad with its peak located at about 480 nm. Prototyped thin-film display panels were developed using the naturally oxidized polypyrrole as active medium.

Abstract: The defects of LED wafer may be caused from the manufacturing environments such as contamination. The appearance of the defects can results in functional faults of LED wafer. Therefore, it is very necessary to detect the defects in LED wafer. In this paper, a new method is presented for the defect feature acquisition of LED wafer, the method uses region growing to segment the LED wafer image in order to acquire the defect features. The clustering strategy is added to the region growing for enhancing the acquisition precision of defect features. The defect features that have been obtained can be used to detect these defects of LED wafer. The method consists of following two steps. First of all, the original image of LED wafer is partitioned into several sub-blocks that are not overlapped, and then these sub-blocks are segmented by clustering strategy. Secondly, the whole wafer image is segmented by using region growing algorithm.

Abstract: Chiral nematic liquid crystals prepared with Grandjean texture demonstrate a photonic bandgap whose central wavelength is proportional to the pitch length, P, of the liquid crystal and whose width is given by (n_e – n_o)P. We show that methyl red doped chiral nematics undergo a shift in the photonic bandgap upon photo-isomerization. This shift is a result of (1) photo-induced change in anchoring energy on the nematic surface, and (2) change in the natural pitch length from the photo-isomerization of the azo dye.

Abstract: Based on liquid crystal electrically controlled birefringence, the paper theoretically deduces liquid crystal variable retarders’ (LCVRs) electrically controlled phase retardation characteristics, and establishes a mathematical analysis model which has been validated in experiment. With the fitting of research results and theoretical calculation of liquid crystal variable retarders’ electrically controlled phase retardation characteristics, a progress is made for us to further survey and understand LCVRs’ properties.

Abstract: By means of the full leaky guided mode technique, the transmittance of the full leaky waveguide geometry which consists of pyramid, matching fluid of refractivity, the vertical alignment nematic liquid crystal cell are investigated experimentally. The experimental curves with different voltages between polarization-conserving transmittance Tss and the internal angle (the angle of incidence for which light is incident on the vertical alignment liquid crystal cell) are obtained. Comparing these experimental curves with the theoretical curves obtained from multi-layer optics theory, the director profile of vertical alignment nematic liquid crystal cell for different voltages is determined.

Abstract: An electrically controlled optical chopper based on holographic polymer dispersed liquid crystal grating (H-PDLC) and its application within the fluorescence microscopy has been investigated in this paper. The H-PDLC chopper has the characteristics such as free waveform, easy and precise tunable working frequency, no moving parts etc. In order to testify its application, a two-channel frequency division multiplexing confocal fluorescence microscopy (FDMCF) has been established, where the integrated H-PDLC chopper array modulates the individual exciting laser beam with different carrying frequency. The FDMCF microscopy detects two-channel fluorescent signals from the two different spots of the specimen’s surface synchronously. The successful experiments testified the optical chopper device based on H-PDLC technique, and explored its application possibility within the modern integrated optical system as well.