Masking device for a color cathode-ray display tube with a flat screen, of the type comprising a support frame for a tensioned shadowmask, and tensioned shadowmask

摘要

Masking device for a color cathode-ray display tube with a flat scree, of the type comprising a support frame for a tensioned shadowmask and a tensioned shadowmask mounted on the support frame so as to undergo tensioning at room temperature, in which device the support frame is made of a hardened Fe—Ni alloy having a thermal expansion coefficient between 20° and 150° C. of less than 5×10^{31 6} K^−1 and a yield stress R_p0.2 at 20° C. of greater than 700 MPa, and the tensioned shadowmask is made of a hardened FeNi or Fe—Ni alloy having a thermal expansion coefficient between 20° C. and 150° C. of less than 5×10^−6 K^−1.