Glass microspheres for use in films and projection screen displays and methods
Assignee3M Innovative Properties Company
InventorsGeoffrey P. Morris, Jacqueline C. Rolfs, Leo A. Meyer, Robert S. Moshrefzadeh, Hsin-Hsin Chou, Billy J. Tompkins, Thomas N. Davis
Life of this patent
Estimating the term…
Abstract
Glass microspheres and rear projection screens containing glass microspheres, which combine a desirable index of refraction (preferably, no greater than about 1.70) and low levels of defects (e.g., bubbles, visible haziness, frostiness, or opacity, substantially nonspherical shapes) upon formation are provided. Also provided is a coating method of placing microspheres on a film for use in a rear projection screen.
Claims20
A projection screen comprising a plurality of glass microspheres in optical contact with a substrate and embedded in an opaque matrix;
- wherein the glass microspheres:
- have an index of refraction of no greater than about 1.70;
- comprise, on a theoretical oxide basis based on the amount of starting materials:
- greater than about 5 wt-% of an alkali metal oxide selected from the group consisting of Na2O, K2O, Li2O, and mixtures thereof;
- no greater than about 40 wt-% SiO2;
- and
- no less than about 10 wt-% TiO2;
- and
- as produced have less than about 15% defects in a population.
A projection screen comprising a plurality of glass microspheres in optical contact with a substrate and embedded in an opaque matrix;
- wherein the glass microspheres:
- have an index of refraction of no greater than about 1.70;
- comprise, on a theoretical oxide basis based on the amount of starting materials:
- no greater than about 40 wt-% SiO2;
- no less than about 10 wt-% TiO2;
- no less than about 5 wt-% B2O3;
- no less than about 20 wt-% of an alkaline earth modifier selected from the group consisting of BaO, SrO, and mixtures thereof;
- and
- greater than about 5 wt-% of an alkali metal oxide selected from the group consisting of Na2O, K2O, Li2O, and mixtures thereof.
A film comprising a plurality of glass microspheres disposed on a substrate and embedded in an opaque matrix;
- wherein the glass microspheres:
- have an index of refraction of no greater than about 1.70;
- comprise, on a theoretical oxide basis based on the amount of starting materials:
- greater than about 5 wt-% of an alkali metal oxide selected from the group containing of Na2O, K2O, Li2O, and mixtures thereof, with the proviso that Li2O is present;
- no greater than about 40 wt-% SiO2;
- and
- no less than about 10 wt-% TiO2;
- and
- as produced have less than about 15% defects in a population.
A glass microsphere comprising, on a theoretical oxide basis, based on starting materials:
- no greater than about 40 wt-% SiO2;
- no less than about 10 wt-% TiO2;
- no less than about 5 wt-% B2O3;
- no less than about 20 wt-% of an alkaline earth modifier selected from the group containing of BaO, SrO, and mixtures thereof;
- and
- greater than about 5 wt-% of an alkali metal oxide selected from the group containing of Na2O, K2O, Li2O, and mixtures thereof, with the proviso that Li2O is present.
A noncalcium-containing glass microsphere comprising, on a theoretical oxide basis, based on starting materials:
- no greater than about 40 wt-% SiO2;
- no less than about 10 wt-% TiO2;
- no less than about 5 wt-% B2O3;
- no less than about 20 wt-% of an alkaline earth modifier selected from the group containing of BaO, SrO, and mixtures thereof;
- and
- greater than about 5 wt-% of an alkali metal oxide selected from the group containing of Na2O, K2O, Li2O, and mixtures thereof.
A method of making a film for use in a projection screen, the method comprising:
- providing a substrate having an opaque matrix disposed thereon;
- and
- applying glass microspheres from a rolling bank of microspheres onto the opaque matrix under conditions effective to produce microspheres in optical contact with the substrate and embedded in the opaque matrix.
Dependencies are inferred from the claim text.