Abstract Glass for the envelope of television display cathode-ray tubes, particularly for the face plate of a colour display tube and having a composition in % by weight within the range limited as follows: ______________________________________ SiO 2 54-69
Na 2 O
6-10
[Na 2 O] + [K 2 O] combined 14-20
K 2 O
5-10
CaO 0- 4
MgO 0-2.5
Al 2 O 3 0- 6
[Al 2 O 3 ] + [ZrO 2 ] < 6
ZrO 2 0- 6
BaO 8-18 2 [ZrO 2 ] + [BaO] + [ZnO] +
4 [Sb 2 O 3 ] > 20
ZnO 0- 5 [ZrO 2 ] + [ZnO] + [Sb 2 O 3 ] > 3
CeO 2 0.05-0.3
Sb 2 O 3 0- 3
[Sb 2 O 3 ] + [As 2 O 3 ]
≧ 0.3
As 2 O 3 0-0.3
______________________________________
Glass for envelope of television display cathode-ray tubes, particularly intended for the face plate of the tube consisting essentially of the composition in % by weight ______________________________________
SiO.sub.2
60 - 63
Na.sub.2 O
7 - 9
[Na.sub.2 O] + [K.sub.2 O] 15-18
K.sub.2 O
7 - 10
Al.sub.2 O.sub.3
0 - 3
MgO + Ca0
1 - 3
BaO 11 - 15
[BaO] + 2 [ZrO.sub.2 ] > 18
ZrO.sub.2
3 - 5
Sb.sub.2 O.sub.3
0 - 1 [ZrO.sub.2 ] + [Al.sub.2 O.sub.3 ] < 6
[Sb.sub.2 O.sub.3 ] + [As.sub.2 O.sub.3 ]
As.sub.2 O.sub.3
0 - 0.3 combined ≧ 0.3
CeO.sub.2
0.05 - 0.3
______________________________________ wherein the temperature difference between the softening point and the annealing point of said glass is at least 190° C, wherein said glass has an annealing point of at least 485° C, wherein said glass has a coefficient of expansion of approximately 100 × 10 -7 between 30° and 300° C and wherein a screen of said glass approximately 11 mm. thick transmits no more than 0.5 mr/h measured at a distance of 5. cms. from the screen when struck by a stream of electrons developed by an electrode having an acceleration voltage of up to 40K volts at an anode current of approximately 300μa.
Claim 2
Dependent Claim
211 words
Glass for envelope of television display cathode-ray tubes, particularly intended for the face plate of the tube consisting essentially of the composition in % by weight ______________________________________
SiO.sub.2
60 - 63
Na.sub.2 O
7 - 9
[Na.sub.2 O] + [K.sub.2 O] 15-18
K.sub.2 O
7 - 10
Al.sub.2 O.sub.3
0 - 3
MgO + Ca0
1 - 3
BaO 11 - 15
[BaO] + 2 [ZrO.sub.2 ] > 18
ZrO.sub.2
3 - 5
Sb.sub.2 O.sub.3
0 - 1 [ZrO.sub.2 ] + [Al.sub.2 O.sub.3 ] < 6
[Sb.sub.2 O.sub.3 ] + [As.sub.2 O.sub.3 ]
As.sub.2 O.sub.3
0 - 0.3 combined ≧ 0.3
CeO.sub.2
0.05 - 0.3
______________________________________ wherein the temperature difference between the softening point and the annealing point of said glass is at least 190° C, wherein said glass has an annealing point of at least 485° C, wherein said glass has a coefficient of expansion of approximately 100 × 10 -7 between 30° and 300° C and wherein a screen of said glass approximately 11 mm. thick transmits no more than 0.5 mr/h measured at a distance of 5. cms. from the screen when struck by a stream of electrons developed by an electrode having an acceleration voltage of up to 40K volts at an anode current of approximately 300μa.
Claim 3
Dependent Claim
40 words
Glass as claimed in claim 1, consisting essentially of the following composition in % by weight: ______________________________________
SiO.sub.2
61.4 BaO 13.6 CeO.sub.2
0.2
Na.sub.2 O
8.8 ZrO.sub.2 3.0
K.sub.2 O
7.8 Al.sub.2 O.sub.3
2.6
CaO 2.0 Sb.sub.2 O.sub.3
0.6
______________________________________