Glass filter for contrast enhancement in CRT displays
AssigneeHoya Corporation
InventorToshiharu Yamashita
Life of this patent
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Abstract
A green contrast enhancement filter for CRT display devices which is prepared by adding about 0.1 to 1.5 part by weight of Cr.sub.2 O.sub.3, about 0 to 0.5 part by weight of CuO and about 0 to 0.2 part by weight of NiO to 100 parts by weight of a base glass comprising about 4 to 70% by weight of SiO.sub.2, about 15 to 30% by weight of Nd.sub.2 O.sub.3, about 0 to 25% by weight of one or more alkali metal oxides (R.sub.2 O) and about 0 to 46% by weight of one or more divalent metal oxides (RO) such as MgO, CaO, SrO, BaO, ZnO and PbO, wherein the sum R.sub.2 O+RO is about 10 to 50% by weight, about 0 to 25% by weight B.sub.2 O.sub.3, about 10% by weight or less Al.sub.2 O.sub.3 and about 0 to 10% by weight each of TiO.sub.2, ZrO.sub.2, La.sub.2 O.sub.3, Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5.
Claims6
A green filter glass having a sharp transmission peak in only the wavelength range of 540 to 550 m.mu. where the peak transmittance is to 10 to 16% through which 2 to 4% light having a wavelength of 610 to 620 m.mu. passes together with the light in the 540 to 550 m.mu. transmission peak consisting essentially of:
- about 0.1 to 1.5 part by weight Cr.sub.2 O.sub.3,
- about 0 to 0.5 part by weight CuO,
- about 0 to 0.2 part by weight NiO and
- 100 parts by weight of a base glass composition consisting essentially of:
- about 4 to 70% by weight SiO.sub.2
- about 15 to 30% by weight Nd.sub.2 O.sub.3
- about 0 to 25% by weight of an alkali metal oxide (R.sub.2 O) and
- about 0 to 46% by weight of a divalent metal oxide (RO) such that the sum of R.sub.2 O and RO is about 10 to 50% by weight
- about 0 to 25% by weight B.sub.2 O.sub.3
- about 0 to 10% Al.sub.2 O.sub.3 and
- about 0 to 10% by weight of each of TiO.sub.2, ZrO.sub.2, La.sub.2 O.sub.3, Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5.
Dependencies are inferred from the claim text.