Because electrodes in AC-PDPs are covered with a layer of dielectric, panels are driven by using a wall charge. The driving sequence of an AC-PDP can be divided into three periods, “an addressing period” “a sustained-discharge period” and “an erasing period”. These periods are related to each other. For example, the erasing period needs not only an erasing movement but also a consistent addressing movement. In one of such erasing discharges, there is a self-erase discharge. A self-erase discharge is a result of applying a high voltage. However, because high voltage generates low contrast, low voltage should be used to generate self-erase discharges. In this paper, we investigate the movement of a wall charge during an erase pulse. First, we examine the relationship between an erase margin and erase-pulse conditions. Next, we investigate a residual wall charge after an erase pulse by measuring the voltage stored in the measurement capacitor. We conclude that a self-erase discharge is good for address movements because resident wall charges don't change with changes in the pulse width and applied voltages. We also describe the conditions under which a self-erase discharge can be easily generated.
This paper describes new sustain waveforms that increase luminance efficiency in AC-PDPs. These waveforms induce self-erase discharges that decrease the current peak of discharges, and enable highly efficient generation of UV light from a discharge. We have obtained a more than 15% higher efficiency with an optimized waveform compared to the efficiency obtained by conventional waveforms in a XGA AC-PDP with a 40-inch diagonal, we also describe another new waveform that strongly promotes a self-erase discharge. Our results show that it enables a luminance efficiency that is 32% higher than that obtained by conventional waveforms in a 4-inch panel.
To investigate why green cells require higher ramp setup voltages, we measured the discharge characteristics of red, green and blue cells while applying a ramp setting waveform to the cells. We found that the secondary-electron emission yields (γ) and the capacitance of the green phosphor layer are smaller than those of the red and blue phosphor layers. We tried to improve the uniformity of discharge characteristics by using new green phosphor, YBO3 : Tb3+. We found that γ and the capacitance increase in proportion to the mixture ratio of the new green phosphor. By using the new green phosphor, we were able to improve the uniformity of addressing characteristics in red, green and blue cells and develop a product with a reduced setup voltage.
In picture-tube design, the nature of a shadow mask curvature and that of a correction lens appear to be different. However, in reality, there are many similarities between the two. Firstly, curvatures are expressed by first-order differential equations. Secondly, test tubes are made using a tentative curvature to acquire information on the direction from which electron beams impinge on the panel. Further, depending on the curvature, it is necessary to manipulate numerical data to eliminate the non-integrability of given equations. This paper describes a method that enables solving such curvature problems directly by using the least square approximate polynomial. The method can be used whenever the equations are non-integrable. The method is illustrated using a shadow mask design for stripe-screen tubes.
A high-performance 46 cm flat-face CDT has been developed using pressed-shadow-mask technology. Despite the flatness of the panel's outer surface, the inner surface is slightly concave to give the mask sufficient strength against shock deformation. The pressed-mask suppresses the penetration of the terrestrial magnetic field and the mask-doming phenomena without the additional outer shield and the doming correction circuit, provides cost-effective display stable color purity. The use of the concave inner surface, which does not increase the miss-convergence and raster distortion, reduces the cost of the correction circuitry. A light-absorbing filter is coated on the inner surface of the panel to reduce the reflection of ambient light. A resistance layer with graded transmittance is coated on the outer surface to improve brightness uniformity. A U-Invar mask with its modified mask-hole cross-sectional structure is used to further increase the mask strength up to that of conventional CDTs.
We describe a software-based method for the demodulation of FM-multiplexed signals in a DGPS receiver by using a 32-bit embedded microprocessor. Demodulation is needed to extract DGPS data from FM-multiplexed signals in DGPS receivers. Currently, dedicated hardware is required for demodulation because it involves many operations. The proposed method based on the use of software, enables demodulation of FM-multiplexed signals by using a 32-bit embedded microprocessor, thus reducing the size and cost of DGPS receivers. Because LMSK demodulation takes up most of the data-processing time in the demodulation of FM-multiplexed signals, the proposed method focuses on mixing, carrier generation, and accumulation of LMSK demodulation. Practical evaluation of this method shows that the processing load for demodulation of FM-multiplexed signals is 12.4 MIPS, while that for GPS receiver using a DGPS receiver is 48.7 MIPS. These results indicate that the proposed method is practical.
With the advance of multimedia technology, the frequency of exposure to artificial visual information has been increasing. The physiological damages caused by visual information which is fewer conformable to human brain has become a serious social problems. We must take into account the fact that visual information mediated by electronic communication systems has different characteristics compared to those of natural information. The granularity of an image presented via a visual medium depends on the resolution of the medium, and it differs from that of the original image. We investigated human KANSEI reactions to the difference in visual granularity by using recorded electroencephalographic alpha activity and the Scheffe' s paired comparison method, based on our previously developed methods. Our results suggest that finer visual images having a fractal structure increase the occipital activity in alpha EEG and give better impression than rougher images.
To reduce raster moire fringes appearing on color CRTs, a technique to simulate moire patterns is needed. Although it is necessary to know the moire pattern appearing on the entire screen of a CRT, the Fourier analysis technique can be used only for a small area where the parameters can be assumed to be uniform. Because there are many different moire modes, we need different methods to simulate the moire patterns. Therefore before doing a simulation, we must identify the mode. In this respect it is difficult to simulate patterns consisting of combined modes. Also, slot-type shadow masks and dot-type shadow masks must be evaluated and analysis should be performed for any electron beam profile. In this paper, a Gaussian-weighting method is described for moire evaluation. In the method, the luminance of phosphor dots around a particular central dot is weighted depending on the distance from the central dot, which simulates the characteristics of a human eye. By using the method, moire patterns of various modes, including combined modes, can be simulated for the entire screen area.
Our visual characteristics are affected by our visual environment. In this experiment, we examined how object colors are perceived in dense fog. Seven male subjects with normal color vision were asked to evaluate their perception of object colors in dense fog. The subjects' task was to match the apparent color of ten standard-color cards in dense fog to the Munsell color. In fog, the subjects' ability to determine colors decreased dramatically both in the chroma and value. That is, their color perception shifted from the perception of chromatic colors to that of achromatic colors. Our results can contribute to research of color perception in visual environments that include fog.