An Evaluation Method for CRT Moire Patterns by Visibility Estimation and Image Simulation

Naoki SHIRAMATSU  Shuji IWATA  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E80-C   No.8   pp.1095-1100
Publication Date: 1997/08/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Advanced Emissive Displays)
Category: 
Keyword: 
cathode ray tube,  moire pattern,  electron beam,  shadow mask,  image simulation,  

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Summary: 
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.