Optical sheet, image source unit and image display device
An object is to provide an optical sheet that keeps efficiency of light utilization high or prevents something bad from occurring in a screen, while having a light blocking effect. Included are a substrate layer; and an optical function layer that is layered on the substrate layer, and has a plurality of light transmission parts which are arranged in a row so as to be light-transmissive, and light absorption parts that are arranged between adjacent ones of the light transmission parts so as to be light-absorptive. A cross-sectional area of each of the light transmission parts to a total cross-sectional area of one of the light transmission parts and one of the light absorption parts which are adjacent to each other is 78.2% to 88.5%, or optical diffuse reflectance of the optical sheet in a light output surface side is 1.9% to 3.5%.
1. An image source unit, comprising:
a surface light source device;
an optical sheet arranged on a light emission side of the surface light source device; and
a liquid crystal panel arranged across the optical sheet on an opposite side from the surface light source device,
the optical sheet comprising:
a substrate layer; and
an optical function layer that is layered on one surface of the substrate layer, and has a plurality of light transmission parts which are arranged in a row along a surface of the substrate layer so as to be light-transmissive, and light absorption parts in a row, each of which is arranged between adjacent ones of the light transmission parts so as to be light-absorptive,
wherein optical diffuse reflectance of the optical sheet in a light output surface side is 1.9% to 3.5% when measured under the condition in which light is irradiated to a light output surface of the optical sheet and the light is not reflective on a surface opposite to the light output surface, and excluding regular reflection components by the optical sheet and the light of components transmitted through the optical sheet, and
wherein each light absorption part has a trapezoidal cross-section in a thickness direction of the optical functional layer; and in a state where the optical sheet is installed in an image display device and the image display device is installed in a car, the light absorption part extends in a horizontal direction and a lower leg part of the trapezoidal cross-section forms an inclined angle with the horizontal plane larger than an inclined angle formed by an upper leg part of the trapezoidal cross-section with the horizontal plane.
2. The image source unit according to claim 1 , wherein optical diffuse reflectance of the optical sheet in a light input surface side is 2.5% to 5.0%.
3. The image source unit according to claim 1 , wherein
each of the light transmission parts has a cross-section of a trapezoid, an shorter upper base of the trapezoid thereof facing the surface light source device, a longer lower base of the trapezoid thereof facing the liquid crystal panel, each of the light absorption parts has a cross-section of a trapezoid, a longer lower base of the trapezoid thereof facing the surface light source device, a shorter upper base of the trapezoid thereof facing the liquid crystal panel.
4. An image display device comprising:
a housing; and
the image source unit according to claim 1 which is arranged inside the housing.
5. The image source unit according to claim 1 , wherein in a cross-section of the optical function layer in a layer thickness direction, a cross-sectional area of one of the light transmission parts to a total cross-sectional area of one of the light transmission parts and one of the light absorption parts which are adjacent to each other is 78.2% to 88.5%.
6. The image source unit according to claim 1 , wherein a longer lower base of the trapezoid of each light transmission part is 37 μm or less.
7. An image source unit comprising:
a surface light source device;
an optical sheet arranged in a light emission side of the surface light source device; and
a liquid crystal panel arranged across the optical sheet on an opposite side from the surface light source device,
the optical sheet comprising:
a substrate layer; and
an optical function layer that is layered on one surface of the substrate layer, and has a plurality of light transmission parts which are arranged in a row along a surface of the substrate layer so as to be light-transmissive, and light absorption parts in a row, each of which is arranged between adjacent ones of the light transmission parts so as to be light-absorptive,
wherein optical diffuse reflectance of the optical sheet in a light output surface side is 1.9% to 3.5% when measured under the condition in which light is irradiated to a light output surface of the optical sheet and the light is not reflective on a surface opposite to the light output surface, and excluding regular reflection components by the optical sheet and the light of components transmitted through the optical sheet, and
wherein each light absorption part has a trapezoidal cross-section in a thickness direction of the optical functional layer; in a state where the optical sheet is installed in an image display device and the image display device is installed in a car, the light absorption part extends in a horizontal direction and an upper leg part of the trapezoidal cross-section forms an inclined angle with the horizontal plane larger than an inclined angle formed by a lower leg part of the trapezoidal cross-section with the horizontal plane; and the lower leg part is parallel to the normal line to the layer surface of the optical functional layer.
8. The image source unit according to claim 7 , wherein optical diffuse reflectance of the optical sheet in a light input surface side is 2.5% to 5.0%.
9. The image source unit according to claim 7 , wherein
each of the light transmission parts has a cross-section of a trapezoid, an shorter upper base of the trapezoid thereof facing the surface light source device, a longer lower base of the trapezoid thereof facing the liquid crystal panel, each of the light absorption parts has a cross-section of a trapezoid, a longer lower base of the trapezoid thereof facing the surface light source device, a shorter upper base of the trapezoid thereof facing the liquid crystal panel.
10. An image display device comprising:
a housing; and
the image source unit according to claim 7 which is arranged inside the housing.
11. The image source unit according to claim 7 , wherein in a cross-section of the optical function layer in a layer thickness direction, a cross-sectional area of one of the light transmission parts to a total cross-sectional area of one of the light transmission parts and one of the light absorption parts which are adjacent to each other is 78.2% to 88.5%.
12. The image source unit according to claim 7 , wherein a longer lower base of the trapezoid of each light transmission part is 37 μm or less.