Reducing moire is an important consideration in CRT design. This paper aims to investigate how the visibility of the inverse-phase raster moire, a typical pattern of the raster moire, is influenced by the distribution of the electron beam and the structure of shadow mask apertures. First, a simple model based on the luminance distribution on the CRT screen and characteristics of the human vision was used to calculate the perceived intensity of the inverse-phase raster moire. This calculation was made to examine the effect of model parameters. It showed that the inverse-phase raster moire consists of (1,1)-order moire components. It was also found that the perceived intensity increases with a decrease in electron beam diameter and with an increase in horizontal aperture pitch. In addition, a subjective evaluation test was conducted using an inverse-phase moire pattern reproduced by the image simulation. Test results agreed with the calculated results. Finally, it was revealed that when an electron beam shape having a Gauss distribution was used, most of the raster moire is the inverse-phase raster moire caused by the (1,1)-order component, while the (2,2)-order moire component was very low.

Feasibility of a color shutter using ferroelectric liquid crystal polymer panel and a field sequential ultra high-resolution CRT with the color shutter as a color field-switching device was studied. The color shutter consists of ferroelectric liquid crystal polymer panels and color polarizers. First, evaluation indices of the color shutter, such as the color gamut, the average transmittance and the white chromaticity shift, were formulated, and the simulation of evaluation indices was examined, where the spectral transmittance characteristics of the polarizer were changed in steps. It was indicated that there was a tradeoff between the color gamut and the average transmittance of the color shutter, and the shutter configuration that provides 0.096 (63% to NTSC) color gamut and 4.3% average transmittance was selected based on the simulation results. Next, the three-line simultaneous scanning method of the monochrome CRT was improved so that the disturbance due to the raster modulation was eliminated by averaging the distribution of beam luminance apparently. To confirm results of the study, the prototype of 21-inch screen size was produced, and the following display characteristics was obtained: luminance of 71 cd/m2, contrast ratio of 146:1 and color gamut of 0.096 (63% to NTSC) under the standard room lighting environment.

A method for measuring the luminance distribution of an electron beam spot was described, which is fundamental to evaluate the resolution of a color display tube. First, to achieve high sensitivity and wide dynamic range identical to those of visual inspection, we proposed the use of an ICCD camera for imaging and two levels of sensitivity. With that method, we were able to measure the luminance distribution of an electron beam spot over a range of currents that extends from the extremely weak cathode current region to large current that correspond to the peak luminance. Specifically, we were able to measure the entire distribution shape from the base to the peak for beam spots in the cathode current range from 20 µA to 300 µA, while compensating the absolute luminance level. Second, a reconstruction algorithm of entire beam distribution from the shape of the masked part of the beam was also proposed, in which shift error is compensated to reduce the variance in measurement results caused by jitter noise in the conventional image processing method. That algorithm improves the reproducibility of repeated measurements. Specifically, a function for estimating the actual shift from the first-order moment of the image was incorporated into the spot shape reconstruction algorithm, resulting in a reduction of the standard deviation for repeated measurements of the horizontal beam spot diameter at 5% intensity from 0.02 mm to 0.005 mm.

The high resolution CRT displays used for computer monitor and high performance TV often produce a pattern of bright and dark stripes on the screen called a moire pattern. The elimination of the moire is an important consideration in the CRT design. In this paper, we propose a method for evaluating a moire pattern based on the measurement data of the electron beam distribution. (1) We describe a mathematical expression of the process whereby a moire pattern is produced. By applying the electron beam measurement data into the formulae, precise value of the period and the contrast of a moire are calculated from the actual data of the electron beam profile and the distribution of apertures of the shadow mask. (2) The visibility of the moire is evaluated by plotting the calculation results on the contrastperiod plane, which consists of visible and invisible moire pattern regions based on experimental results of the psychological tests. (3) In addition to the analysis by calculation, the visibility of moire patterns can be visually examined by simulating moire patterns using the same data as above calculation. Since not only fundamental design parameters such as a shadow mask pitch and a scanning line pitch but also details of an electron beam profile such as a distortion or an asymmetry can be examined, a newly developed method contributes the efficiency of the CRT design.