Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
176 words
A glass for the faceplate of a television picture tube essentially free from PbO and other readily-reducible metal oxides exhibiting an electrical resistivity, when measured at 350° C., of at least 10 7 ohm-cm, a coefficient of thermal expansion (0°-300° C.) not in excess of 102×10 -7 /°C., an internal liquidus under 900° C., a strain point not over 500° C., a softening point not over 690° C., a linear X-ray absorption coefficient at 0.6 A of at least 35 cm -1 such that X-ray transmittance therethrough will be less than 0.5 mr/hr when measured at a distance of 5 cm from a faceplate of conventional thickness, and strong resistance of discoloration from X-ray and electron bombardment consisting essentially, expressed in weight percent on the oxide basis as calculated from the batch, of: ______________________________________
SiO.sub.2 43-55
Al.sub.2 O.sub.3
0-4
ZnO 5-12
Li.sub.2 O 0.5-3
Na.sub.2 O 4-8
K.sub.2 O 3-8
Li.sub.2 O + Na.sub.2 O +
K.sub.2 O 10-18
CaO 0-5
SrO 2-14
BaO 10-20
CaO + SrO + BaO 16-30
CeO.sub.2 0.3-1
ZrO.sub.2 2-8
______________________________________
Claim 2
Dependent Claim
176 words
A glass for the faceplate of a television picture tube essentially free from PbO and other readily-reducible metal oxides exhibiting an electrical resistivity, when measured at 350° C., of at least 10 7 ohm-cm, a coefficient of thermal expansion (0°-300° C.) not in excess of 102×10 -7 /°C., an internal liquidus under 900° C., a strain point not over 500° C., a softening point not over 690° C., a linear X-ray absorption coefficient at 0.6 A of at least 35 cm -1 such that X-ray transmittance therethrough will be less than 0.5 mr/hr when measured at a distance of 5 cm from a faceplate of conventional thickness, and strong resistance of discoloration from X-ray and electron bombardment consisting essentially, expressed in weight percent on the oxide basis as calculated from the batch, of: ______________________________________
SiO.sub.2 43-55
Al.sub.2 O.sub.3
0-4
ZnO 5-12
Li.sub.2 O 0.5-3
Na.sub.2 O 4-8
K.sub.2 O 3-8
Li.sub.2 O + Na.sub.2 O +
K.sub.2 O 10-18
CaO 0-5
SrO 2-14
BaO 10-20
CaO + SrO + BaO 16-30
CeO.sub.2 0.3-1
ZrO.sub.2 2-8
______________________________________
Claim 3
Dependent Claim
12 words
A glass according to claim 1 also containing 0.5-2% TiO 2 .
Claim 4
Dependent Claim
67 words
A glass according to claim 2 consisting essentially, expressed in weight percent on the oxide basis as calculated from the batch, of: ______________________________________
SiO.sub.2 48-53
Al.sub.2 O.sub.3
1-2
ZnO 7-11
Li.sub.2 O 1-3
Na.sub.2 O 5-7
K.sub.2 O 5-6
Li.sub.2 O + Na.sub.2 O +
K.sub.2 O 11-16
CaO 0-3
SrO 3-7
BaO 14-16
CaO + SrO + BaO 18-24
ZrO.sub.2 2-7
CeO.sub.2 0.4-0.8
TiO.sub.2 0.5-1.0
______________________________________