By a News Reporter-Staff News Editor at Journal of Engineering -- NIPPON SHEET GLASS COMPANY, LIMITED (Tokyo, JP) has been issued patent number 9664822, according to news reporting originating out of Alexandria, Virginia, by VerticalNews editors.
The patent's inventors are Kondo, Fumiyoshi (Hyogo, JP); Yabuta, Takeshi (Hyogo, JP); Kawazu, Mitsuhiro (Hyogo, JP).
This patent was filed on July 9, 2013 and was published online on May 30, 2017.
From the background information supplied by the inventors, news correspondents obtained the following quote: "A cover glass is usually disposed on the light incident side of a so-called crystal type photoelectric conversion device. However, when the photoelectric conversion device is installed on the roof of a house, reflected light from the cover glass may cause annoyance to neighboring houses. Therefore, in the cases where attention should be paid to reflected light, such as when the photoelectric conversion device is installed on the roof of a house, a cover glass is used which has asperities formed in its surface to disperse reflected light.
"The shape of surface asperities has influence on the amount of light transmitted through a cover glass. Thus, there have been reported attempts to optimize the shape of surface asperities of a cover glass in order to improve the photoelectric conversion efficiency. For example, Patent Literature 1 discloses a cover glass having semi-spherical recesses formed in its surface. The shape and arrangement of the recesses of this cover glass are designed to increase the amount of light transmitted through the cover glass during daytime over the course of a year. When recesses are formed for such purposes, the depth of the recesses is set deeper than when recesses are formed only for the purpose of anti-glare.
"In order to increase the light transmittance of a transparent substrate typified by a glass sheet, a reflection-reducing film is formed on a surface of the substrate in some cases. A most frequently used reflection-reducing film is a dielectric film obtained by vacuum deposition, sputtering, chemical vapor deposition (CVD), or the like. A fine particle-containing film containing fine particles such as fine silica particles is also used as the reflection-reducing film in some cases. The fine particle-containing film is formed by applying a coating liquid containing the fine particles onto the transparent substrate by means of dipping, flow coating, spraying, or the like.
"With a reflection-reducing film formed on that surface of a cover glass which has surface asperities, the appearance may be significantly deteriorated due to uneven reflection. In order to reduce the deterioration in appearance, for example, Patent Literature 2 discloses a cover glass for photoelectric conversion devices that includes a reflection-reducing film and in which the shape of surface asperities of a glass sheet and the number of layers of fine silica particles stacked in valley portions of the surface asperities and on peak portions of the surface asperities are adjusted. This cover glass has a reflectance of 1.5% or more and 3% or less over the entire wavelength range of 380 nm to 780 nm for light incident on a side on which the reflection-reducing film is formed; thus, the deterioration in appearance due to uneven reflection is reduced."
Supplementing the background information on this patent, VerticalNews reporters also obtained the inventors' summary information for this patent: "Technical Problem
"In a cover glass for photoelectric conversion devices in which a reflection-reducing film containing fine silica particles is formed over surface asperities of a glass sheet, a transmittance gain obtained by subtracting an average transmittance of the glass sheet alone from an average transmittance of the cover glass for light incident on the reflection-reducing film side is an important factor for the performance of the cover glass for photoelectric conversion devices. The higher the transmittance gain of the cover glass is, the more the amount of light transmitted through the cover glass is, and the higher the efficiency of the photoelectric conversion device is. However, the cover glass described in Patent Literature 2 has room for improvement in transmittance gain.
"In view of such circumstances, the present invention aims to increase the transmittance gain of a cover glass for photoelectric conversion devices in which a reflection-reducing film containing fine silica particles is formed over surface asperities of a glass sheet.
"Solution to Problem
"The present invention provides a cover glass for photoelectric conversion devices, the cover glass including:
"a glass sheet having surface asperities; and
"a reflection-reducing film formed over the surface asperities of the glass sheet.
"The surface asperities of the glass sheet have an average spacing Sm of 0.3 mm or more and 2.5 mm or less and an arithmetic average roughness Ra of 0.3 .mu.m to 5 .mu.m,
"the reflection-reducing film includes fine silica particles having an average particle diameter of 50 to 200 nm and a binder for the fine silica particles,
"the fine silica particles are uniformly arranged in a single layer on peak portions of the surface asperities in such a manner that a filling fraction F is 35 to 65%,
"a transmittance gain is 2.37% or more, the transmittance gain being obtained by subtracting an average transmittance of the glass sheet as measured when light having wavelengths ranging from 380 to 1100 nm are incident on a face of the glass sheet that has the surface asperities, from an average transmittance of the cover glass as measured when light having the wavelengths are incident on a reflection-reducing film side of the cover glass, and
"the filling fraction F is defined by the following formula: F=A/B.times.100, where
"A represents the number of the fine silica particles contained in a square region each of whose sides has a length that is 10 times the average particle diameter of the fine silica particles, and
"B represents the number of spheres filled in the square region when the spheres are assumed to have a diameter equal to the average particle diameter of the fine silica particles and to be arranged in closest packing in the square region.
"Advantageous Effects of Invention
"In the cover glass of the present invention, the average particle diameter of the fine silica particles contained in the reflection-reducing film is 50 to 200 nm, and the fine silica particles are uniformly arranged on the peak portions of the surface asperities in such a manner that the filling fraction F is 35 to 65%. Thus, the fine silica particles are arranged on the peak portions of the surface asperities at an appropriate density; consequently, the cover glass of the present invention exhibits a high transmittance gain."
For the URL and additional information on this patent, see: Kondo, Fumiyoshi; Yabuta, Takeshi; Kawazu, Mitsuhiro. Cover Glass for Photoelectric Conversion Device. U.S. Patent Number 9664822, filed July 9, 2013, and published online on May 30, 2017. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=9664822.PN.&OS=PN/9664822RS=PN/9664822
Keywords for this news article include: NIPPON SHEET GLASS COMPANY LIMITED.
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