Reduced glare neodymium oxide containing window glass

Details Reduced glare neodymium oxide containing window glass Reduced glare neodymium oxide containing window glass

2000-10-16

2002-07-09

Turner, Archene (Department: 1775)

Stock material or miscellaneous articles

Composite

Of quartz or glass

C501S064000, C501S903000, C501S904000

Reexamination Certificate

active

06416867

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to the development of a new reduced glare window glass, and in particular a new window glass that will be capable of improving color rendition of viewed objects, and to eliminate much of the discomfort caused by the glare from the sun while at the same time maximizing light transmittance.
BACKGROUND AND THEORY OF THE INVENTION
It has long been recognized that the visual discomfort from glare from the sun coming through windows is a major problem that has not been properly solved up to this time.
Combes (U.S. Pat. No. 5,830,814, (1998)), discloses a glass composition suitable for the manufacture of glazings for use in the architectural field or for fitting in motor vehicles. These compositions contain the following constituents, expressed in weight percentages, defined by the following limits: SiO
2
69 to 75%, Al
2
O
3
0 to 3%, CaO 2 to 10%, MgO 0 to 2%, Na
2
O 9 to 17%, Fe
2
O
3
(total iron) 0.2 to 1.5%. These compositions can also contain fluorine, as well as oxides of zinc, zirconium, titanium and less than 4% barium oxide, the sum of the percentages of the alkaline earths remaining equal to or below 10%.
Sakaguchi et al. (U.S. Pat. No. 5,958,811, (1999)) discloses an ultraviolet and infrared radiation absorbing glass having excellent ultraviolet radiation absorbing power and a bronze or neutral gray tint which is suitably used as a window glass for vehicles of automobiles and also as a window glass for construction materials is provided. The glass comprises, in % by weight: basic glass components comprising 65 to 80% SiO
2
, 0 to 5% B
2
O
3
, 0 to 5% Al
2
O
3
, 0 to 10% MgO, 5 to 15% CaO, 10 to 18% Na
2
O, 0 to 5% K
2
O, 5 to 15% MgO+CaO, and 10 to 20% Na
2
O+K
2
O, and coloring components comprising 0.20 to 0.50% total iron oxide (T-Fe
2
O
3
) in terms of Fe
2
O
3
, 0 to 3% CeO
2
, 0.025 to 6.0% La
2
O
3
, 0 to 2.0% TiO
2
, 0.0002 to 0.005% CoO, 0.0002 to 0.005% Se, 0 to 0.01% NiO, and 0 to 1.0% SnO
2
, wherein 5 to 25% of said T-Fe
2
O
3
in terms of Fe
2
O
3
is FeO.
Hayden et al. (U.S. Pat. No. 4,470,922, (1991)) discloses a strengthenable, high Neodymium-containing glass containing 40 to 60% SiO
2
and 10 to 30% Neodymium Oxide, and various other inorganic compounds in minor amounts.
Kobayashi (U.S. Pat. No. 4,454,446, (1984)) discloses a cathode ray tube for a light source with a face plate being made of a glass material containing the rare earth oxides Nd
2
O
3
and Pr
2
O
3
, so that satisfactory color light and contrast are obtained even under the sun light.
Matsuura (U.S. Pat. No. 3,714,055, (1973)) discloses glass color filters for use in color photography under white and warm white fluorescent lights prepared from a glass composition, containing various glass components one of which is Neodymium Oxide in the amount of 0.3 to 2.5 percent.
Yamashita (U.S. Pat. No. 4,521,524, (1985)), discloses contrast enhancement filters for color CRT display devices which have between 5 and 40% Neodymium Oxide as a component of the glass.
Cook et al. (U.S. Pat No. 4,769,347, (1988)) discloses contrast enhancement filter glass for color CRT displays which has between 10 and 25% Neodymium Oxide as a component of the glass.
Hirano et al. (U.S. Pat. No. 4,315,186, (1982)) discloses a reflective lamp with a Neodymium Oxide doped front lens section fused to a reflective mirror section. Hirano restricts the amount of Neodymium Oxide in the front lens section to a range of 0.5 to 5.0 percent by weight. At an amount of Neodymium Oxide above 5 percent, the difference in the thermal expansion coefficient between the resultant glass material and that constituting the reflective mirror becomes too great, so that it becomes difficult to fuse the front lens section to the reflective mirror base.
Lyman (U.S. Pat. No. 5,076,674, (1991)) discloses a reduced first surface reflectivity electrochemichromic rearview mirror assembly. In the art of Lyman, Neodymium Oxide is one of a number of possible materials of high refractive index in a triple layer thin film stack.
What the present invention does, and what the prior art fails to do, is to reduce the amount of yellow light transmitted through window glass, since reducing the amount of yellow light in the spectrum improves color rendition and reduces glare. The approach of the present invention to the problem of visual discomfort and visual disability is to add Neodymium Oxide, a rare earth oxide, to the window glass to absorb the yellow light and reduce its presence in the spectrum of the transmitted light. The Neodymium Oxide is added to the window glass in an amount greater than 0.0191 grams per square centimeter of glass surface to provide a total maximum transmittance of 72.57 percent. Below this amount, there is insufficient Neodymium Oxide to absorb sufficient yellow light to adequately reduce glare in a satisfactory manner. As window glass is made in various thicknesses, it is necessary to express the amount of Neodymium Oxide necessary to accomplish the goal of glare reduction as a weight per unit surface of glass, rather than as a weight percentage of the glass material.
This invention is important as an energy conservation technology. As glare is reduced by means of absorbing yellow light in the spectrum of the transmitted light, one no longer needs curtains or shades to block out unwanted sunlight, so the glass can be used as a glazing material on the sides of buildings to allow for the use of daylighting in place of interior artificial illumination. Furthermore, by the sides of windows, one can see well under as much as 700 to 7,000 foot-candles of direct sunlight without bothersome glare.
To explain the importance of the present invention, a discussion of its Neodymium Oxide component is as follows:
Neodymium is a rare earth element, having an atomic number of 60 and an atomic weight of 144.24. It combines with oxygen to form Neodymium Oxide, Nd
2
O
3
, having a molecular weight of 336.48.
1
The elucidation of the rare earths in elemental form took the better part of the nineteenth century, and the properties of Neodymium that are important to the lighting art in this patent application were known even before Neodymium was prepared in metallic form. In 1803, Klaproth discovered the mineral ceria. It was also found about the s time by Berzelius and William Hisinger.
2
This mineral proved to be a mixture of various rare earth oxides. In 1814, Hisinger and Berzelius isolated Cerium Oxide from the ceria earth.
3
In 1839, Moslander found the rare earth lanthana in the ceria.
4
In 1841, Moslander treated lanthana with dilute nitric acid, and extracted from it a new rose colored oxide which he called didymium, because as he said, it seemed to be “an inseparable twin brother of lanthana”.
5
It was believed that didymium was a mixture of elements. The separation proved difficult. In 1882, Professor Bobuslav Brauner at the University of Prague examined some of his didymium fractions with the spectroscope and found a group of absorption bands in the blue region (&lgr;=449−443 nanometers) and another in the yellow (&lgr;=590−568 nanometers).
6
In 1885, Welsbach separated didymium into two earths, praseodymia and neodymia.
7
The neodymia has the aborption bands in the yellow region. The neodymia earth is Neodymium Oxide.
The spectra of rare earths became of great interest to a number of investigators. The most impressive feature about the spectra of rare earth ions in ionic crystals is the sharpness of many lines in their absorption and emission bands. As early as 1908, Becquerel realized that in many cases these lines can be as narrow as those commonly observed in the spectra of free atoms of free molecules.
8
However, many solids that are of practical use today are amorphous or glassy rather than crystalline. That means that in the immediate vicinity of like ions in such substances is similar, but that there is no long range order in the sample. Rare earth ions can be easily incorporated into many glasses.
It was noted quite early that in glasses, as mig

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