By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventors Kubo, Yuichiro (Minato-ku, JP); Kawazu, Mitsuhiro (Minato-ku, JP); Shimmo, Katsuhide (Minato-ku, JP), filed on April 8, 2014, was published online on November 17, 2015.
The patent's assignee for patent number 9188720 is Nippon Sheet Glass Company, Limited (Tokyo, JP).
News editors obtained the following quote from the background information supplied by the inventors: "The present invention relates to an infrared cut filter and an imaging apparatus in which an infrared cut filter is used.
"A semiconductor solid-state imaging device such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) is built in imaging apparatus such as digital cameras. The sensitivity of these solid-state imaging devices extends from a visible spectrum range to an infrared spectrum range. For this reason, an infrared cut filter for shielding infrared light is provided between an imaging lens system and a solid-state imaging device in the imaging apparatus. The infrared cut filter enables calibrating the sensitivity of the solid-state imaging device to approximate the spectral sensitivity of human beings.
"Infrared cut filters used in the related art include those manufactured by forming an infrared reflecting layer including a dielectric multilayer film on a resin substrate (see, for example, patent document 1).
"[patent document 1] JP2005-338395
"However, an infrared reflecting layer including a dielectric multilayer has incident angle dependence in which infrared shielding property varies depending on the incident angle. Therefore, the central part of an image capturing light transmitted through the infrared reflecting layer may look different in color from the periphery thereof.
"Also, an infrared cut filter is required to have high abrasion resistance and environmental resistance because it is provided in front of a solid-state imaging device."
As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventors' summary information for this patent: "The present invention addresses the issue and a purpose thereof is to provide an infrared cut filter having favorable infrared shielding property relatively less dependent on the incident angle and having high abrasion resistance and environmental resistance, and to provide an imaging apparatus in which the infrared cut filter is used.
"The infrared cut filter according to at least one embodiment comprises: a transparent dielectric substrate; an infrared reflecting layer formed on one surface of the transparent dielectric substrate and configured to reflect infrared light; and an infrared absorbing layer formed on the other surface of the transparent dielectric substrate and configured to absorb infrared light, and formed by encapsulating infrared absorbing pigment in a matrix formed by a sol-gel method to contain silica as a main component.
"The infrared reflecting layer may be formed of a dielectric multilayer film.
"Given that the wavelength that provides the transmittance of 50% of the infrared reflecting layer is .lamda..sub.RT50% nm and the wavelength that provides the transmittance of 50% of the infrared absorbing layer is .lamda..sub.AT50% nm, the infrared reflecting layer and the infrared absorbing layer may be formed such that .lamda..sub.AT50%<.lamda..sub.RT50% is met.
"The infrared reflecting layer and the infrared absorbing layer may be formed such that .lamda..sub.AT50%-.lamda..sub.RT50%.ltoreq.-10 nm is met.
"The infrared reflecting layer and the infrared absorbing layer may be formed such that .lamda..sub.AT50%-.lamda..sub.RT50%.ltoreq.-20 nm is met.
"The infrared reflecting layer and the infrared absorbing layer may be formed such that .lamda..sub.AT50%-.lamda..sub.RT50%.ltoreq.-30 nm is met.
"The infrared reflecting layer and the infrared absorbing layer may be formed such that -50 nm.ltoreq..lamda..sub.AT50%-.lamda..sub.RT50% is met.
"The infrared absorbing layer may include, as a source material, a mixture of phenyltriethoxysilane and tetraethoxysilane mixed at a ratio between 50:50 and 80:20, both inclusive.
"The transparent dielectric substrate may be formed of glass. The infrared reflecting layer may be formed so as to reflect ultraviolet light.
"A reflection prevention layer for preventing reflection of visible light may be provided on the infrared absorbing layer. The reflection prevention layer may have the function of preventing transmittance of ultraviolet light.
"The infrared reflecting layer may be warped such that the surface opposite to the surface on the side of the transparent dielectric substrate is convex.
"Another embodiment of the present invention relates to an imaging apparatus. The imaging apparatus comprises: the aforementioned infrared cut filter; and an imaging device on which light transmitted through the infrared cut filter is incident.
"Optional combinations of the aforementioned constituting elements, and implementations of the invention in the form of methods, apparatuses, and systems may also be practiced as additional modes of the present invention."
For additional information on this patent, see: Kubo, Yuichiro; Kawazu, Mitsuhiro; Shimmo, Katsuhide. Infrared Cut Filter and Imaging Apparatus. U.S. Patent Number 9188720, filed April 8, 2014, and published online on November 17, 2015. 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=9188720.PN.&OS=PN/9188720RS=PN/9188720
Keywords for this news article include: Electronics, Semiconductor, Nippon Sheet Glass Company Limited.
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