ANALYSIS OF SHADOW MASK THERMAL DEFORMATION AND PREDICTION OF BEAM LANDING SHIFTS FOR COLOR CRT

In the cathode ray tube(CRT), beam landing ships on the phosphor scree n mainly result from the thermal deformation of the mask frame assembl y and deteriorate the color purity. In this paper, the thermal deforma tion of the mask frame assembly is analyzed by using the finite elemen t method(FEM) and the beam landing shifts are predicted. For realistic analysis, the apparent thermal conductivity and the apparent elastic modulus are calculated and the shadow mask is modeled as a shell witho ut apertures. All parts inside the CRT are modeled and the each radiat ive effect is considered. Then the finite element analysis is performe d for transient thermoelastic deformation of the mask frame assembly a nd the beam landing shifts are calculated. Experiments are performed f or 17 '' CRT to validate the FEM analysis. The temperatures of all par ts inside the CRT and beam landing shift on the panel are measured and the results are discussed in comparison with the results of the FEM a nalysis. From the study, we shows that this analysis method can be app licable for designing a mask frame assembly of CRT that brings the lan ding shift to the order of a few micro-meter.