Method for fabricating a glass CRT panel

DETAILED DESCRIPTION In the novel method, soon after forming the panel from a gob of glass, the panel is thermally processed, during the initial annealing stage, for a prescribed time period at about those temperatures above 450.
degree.
C.
that produce minimum compaction, which temperatures are substantially lower than those temperatures that produce minimum surface stress.
After cooling the panel to room temperature, the panel exhibits both lower compaction and higher compressive surface stress than panels which are similarly annealed at the higher temperatures ordinarily used during the initial stage of annealing.
In the preferred embodiments, panels are processed at 470.
degree.
.
+-.
10.
degree.
C.
by the novel method, instead of 500.
degree.
.
+-.
10.
degree.
C.
as in prior methods.
The novel method recognizes that the soak time and temperature employed during the initial stage of annealing of a glass panel directly affect the compaction and surface stresses subsequently exhibited by the panel.
Higher compressive surface stresses in panels reduce the possibility of glass failure, such as by stress corrosion, and could permit using panel surface contours that would otherwise be subject to failure.
A lower degree of compaction in panels reduces the deformations which contribute to misregister between the shadow mask and the phosphor screen in a shadow-mask-type CRT.
Lower compaction in panels may permit the elimination of the time-consuming and costly reheating of the panel at the tube factory.