Backlight device and liquid crystal display configured for uniform light distribution through reflection
First Claim
1. A backlight device comprising:
- a light guiding plate having a light-emitting surface, a rear surface facing in a direction opposite that of said light-emitting surface, and side surfaces interconnecting the light-emitting surface and the rear surface;
one or more concave portions formed into said rear surface and extending toward said light-emitting surface; and
a light-emitting diode light source arranged within each of said one or more concave portions,wherein,at least (i) said light-emitting surface, (ii) said side surfaces of said light-guiding plate, and (iii) said rear surface of the light-guiding plate are configured as a reflective-angle modified portion comprising a rough reflective surface with minute convexities and concavities distributed uniformly across a whole surface of (i) said light-emitting surface, (ii) said side surfaces of said light-guiding plate, and (iii) said rear surface of the light-guiding plate but excludes surfaces of the one or more concave portions, wherein said reflective-angle modified portion modifies a reflective angle of light emitted from said light source so that light within the light-guiding plate having an angle of incidence with respect to the light emitting surface that is greater than a critical angle is reflected back from the light-emitting surface while light within the light-guiding plate having an angle of incidence with respect to the light-emitting surface that is equal to or smaller than the critical angle transmits through the light-emitting surface, the critical angle being that angle at which light totally reflects from said light-emitting surface, wherein the reflective-angle modified portion modifies light incident on the light-emitting surface such that light beams incident on the light-emitting surface have an angle different from a previous angle of incidence on the light-emitting surface; and
wherein the backlight device further includes a reflective film on each of the side surfaces and the rear surface that is operable to reflect light transmitted through the rough reflective surface.
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Accused Products
Abstract
A direct backlight device including a light source arranged on the rear surface of a light-guiding plate and a liquid crystal display apparatus including the backlight device are provided, in which light extracting efficiency from the light-guiding plate is improved and luminance can be prevented from lowering or can be improved. The backlight device includes a light source arranged on the rear surface opposite to a light-emitting surface, and a reflective-angle modified portion, for example, a concave-convex portion formed by sandblast to modify a reflective angle of light emitted from the light source is provided at least on the light-emitting surface and/or the rear surface. A light reflective angle equal to or smaller than the critical angle is modified to improve the light extracting efficiency from the light-emitting surface.
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Citations
19 Claims
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1. A backlight device comprising:
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a light guiding plate having a light-emitting surface, a rear surface facing in a direction opposite that of said light-emitting surface, and side surfaces interconnecting the light-emitting surface and the rear surface; one or more concave portions formed into said rear surface and extending toward said light-emitting surface; and a light-emitting diode light source arranged within each of said one or more concave portions, wherein, at least (i) said light-emitting surface, (ii) said side surfaces of said light-guiding plate, and (iii) said rear surface of the light-guiding plate are configured as a reflective-angle modified portion comprising a rough reflective surface with minute convexities and concavities distributed uniformly across a whole surface of (i) said light-emitting surface, (ii) said side surfaces of said light-guiding plate, and (iii) said rear surface of the light-guiding plate but excludes surfaces of the one or more concave portions, wherein said reflective-angle modified portion modifies a reflective angle of light emitted from said light source so that light within the light-guiding plate having an angle of incidence with respect to the light emitting surface that is greater than a critical angle is reflected back from the light-emitting surface while light within the light-guiding plate having an angle of incidence with respect to the light-emitting surface that is equal to or smaller than the critical angle transmits through the light-emitting surface, the critical angle being that angle at which light totally reflects from said light-emitting surface, wherein the reflective-angle modified portion modifies light incident on the light-emitting surface such that light beams incident on the light-emitting surface have an angle different from a previous angle of incidence on the light-emitting surface; and wherein the backlight device further includes a reflective film on each of the side surfaces and the rear surface that is operable to reflect light transmitted through the rough reflective surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A liquid crystal display apparatus comprising:
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a transmissive liquid crystal display panel; and a backlight device illuminating said liquid crystal display panel from a rear surface side thereof, wherein, said backlight device includes (a) a light-guiding plate having a flat light-emitting surface, a flat rear surface facing in a direction opposite said light-emitting surface, and side surfaces interconnecting the light-emitting surface and the rear surface, (b) one or more concave portions formed into said rear surface and extending toward said light-emitting surface, and (c) a light-emitting diode light source positioned within each of said one or more concave portions, at least (i) said light-emitting surface, (ii) said side surfaces of said light-guiding plate, and (iii) said rear surface of the light-guiding plate comprise a reflective-angle modified portion comprising a rough reflective surface with minute convexities and concavities distributed uniformly across a whole surface of (i) said light-emitting surface, (ii) said side surfaces of said light-guiding plate, and (iii) said rear surface of the light-guiding plate but excludes surfaces of the one or more concave portions, wherein said reflective-angle modified portion modifies a reflective angle of light emitted from said light source so that light within the light-guiding plate having an angle of incidence with respect to the light emitting surface that is greater than a critical angle is reflected back from the light-emitting surface while light within the light-guiding plate having an angle of incidence with respect to the light-emitting surface that is equal to or smaller than the critical angle transmits through the light-emitting surface, the critical angle being that angle at which light totally reflects from said light-emitting surface, wherein the reflective-angle modified portion modifies light incident on the light-emitting surface such that light beams incident on the light-emitting surface have an angle different from a previous angle of incidence on the light-emitting surface; and wherein the backlight device further includes a reflective film on each of the side surfaces and the rear surface that is operable to reflect light transmitted through the rough reflective surface. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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Specification