Temperature compensated shadow mask for a color cathode-ray tube

Claim 1

A color cathode-ray tube having a faceplate section including (a) a rectangular image area bearing deposits of three different phosphor materials defining a multiplicity of phosphor triads, (b) a flange normal to the periphery of said area and (c) support pins extending inwardly from said flange on both sides and on the top and/or bottom of said tube, further having a color-selection electrode of essentially the same size and shape as said image area including (d) a mask component having a field of apertures individually aligned with an assigned one of said triads and (e) a rectangular frame of angular cross section having one part parallel to the axis of the tube to which the peripheral portion of said mask is attached and having another part disposed transverse to said axis, and also having an improved arrangement for mounting said electrode in spaced parallel relation to said image area comprising: a pair of similar elongated leaf springs individually formed of two metallic pieces having different temperature coefficients of expansion, arranged in side-by-side abutting relation and mechanically fastened to one another along their abutting surfaces, said springs facing the same direction relative to the top of said frame with the piece of higher temperature coefficient closer to said image area, said springs being secured at one end to said frame by means of weld connections made only to corresponding points on opposing side portions of said one part of said frame, said springs being contoured to bridge the space between said frame and said support pins on the side portions of said faceplate flange and having an aperture at the opposite end dimensioned to accept said support pins and form a pivoted connection therewith, and the length of each of said springs being proportioned in relation to the aforesaid difference in coefficients of expansion to effect pivotal movement of said springs about their associated pins and axial displacement of said frame toward said image area as the tube attains its operating temperature.