Front light, reflective liquid crystal display device and personal digital assistant
First Claim
1. A front light arranged in front of a display device, comprising:
- a main optical guide plate;
a second optical guide plate having a longitudinal direction extending along a widthwise direction of and at an end of said main optical guide plate, said second optical guide plate having a first end surface facing said main optical guide plate and a second end surface opposite the first end surface, the second end surface including a plurality of grooves extending in a depth direction, and lying along the longitudinal direction, respective prisms being formed by surfaces of said second optical guide plate located between each adjacent pair of said grooves;
a point light source arranged at a longitudinal end of said second optical guide plate; and
a reflective film coating a surface of said grooves.
1 Assignment
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Accused Products
Abstract
A compact and light weight front light, a reflective liquid crystal display device, and a personal digital assistant providing an image display of uniform brightness with high efficiency are provided. The front light includes a main optical guide plate and a second optical guide plate. The second optical guide plate is arranged at an end of the main optical guide plate along the widthwise direction, and, on an end surface opposite an end surface facing the main optical guide plate, grooves forming prisms are aligned along the longitudinal direction, extending in the depth direction. The front light further includes a point light source arranged at an end, in the longitudinal direction, of the second optical guide plate, and a reflective film covering the surfaces of the grooves.
62 Citations
22 Claims
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1. A front light arranged in front of a display device, comprising:
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a main optical guide plate;
a second optical guide plate having a longitudinal direction extending along a widthwise direction of and at an end of said main optical guide plate, said second optical guide plate having a first end surface facing said main optical guide plate and a second end surface opposite the first end surface, the second end surface including a plurality of grooves extending in a depth direction, and lying along the longitudinal direction, respective prisms being formed by surfaces of said second optical guide plate located between each adjacent pair of said grooves;
a point light source arranged at a longitudinal end of said second optical guide plate; and
a reflective film coating a surface of said grooves. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
the end of said main optical guide plate toward said second optical guide plate is tapered from opposing sides such that a central portion of the end portion protrudes most toward said second optical guide plate, the end surface facing said main optical guide plate of said second optical guide plate is tapered from opposing sides such that a central portion of the end surface is recessed most from said main optical guide plate, conforming to the tapered end of said main optical guide plate, and said main optical guide plate and said second optical guide plate are positioned with the tapered ends fitted to each other. -
9. The front light according to claim 1, wherein said reflective film is a thin film of a metal chosen from the group consisting of aluminum, silver, gold, copper, and platinum.
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10. The front light according to claim 1, wherein said reflective film includes an underlying film on said grooves.
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11. The front light according to claim 1, wherein said grooves are roughened.
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12. The front light according to claim 1, including a scattering member scattering light beams of said second optical guide plate, arranged on said first end of said second optical guide plate facing said main optical guide plate.
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13. The front light according to claim 1, wherein said point light source is a light emitting diode.
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14. A reflective liquid crystal display device having a front light on a front side facing a viewer, said front light including
a main optical guide plate; -
a second optical guide plate having a longitudinal direction extending along a widthwise direction of and at an end of said main optical guide plate, said second optical guide plate having a first end surface facing said main optical guide plate and a second end surface opposite the first end surface, the second end surface including a plurality of grooves extending in a depth direction, and lying along the longitudinal direction, respective prisms being formed by surfaces of said second optical guide plate located between each adjacent pair of said grooves;
a point light source arranged at a longitudinal end of said second optical guide plate; and
a reflective film coating a surface of said grooves. - View Dependent Claims (15, 16)
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17. A personal digital assistant provided with a reflective liquid crystal display device including a front light, said front light including
a main optical guide plate; -
a second optical guide plate having a longitudinal direction extending along a widthwise direction of and at an end of said main optical guide plate, said second optical guide plate having a first end surface facing said main optical guide plate and a second end surface opposite the first end surface, the second end surface including a plurality of grooves extending in a depth direction, and lying along the longitudinal direction, respective prisms being formed by surfaces of said second optical guide plate located between each adjacent pair of said grooves;
a point light source arranged at a longitudinal end of said second optical guide plate; and
a reflective film coating a surface of said grooves. - View Dependent Claims (18, 19, 20)
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21. An illumination device for a display device, the illumination device comprising:
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a display element;
a main optical guide plate radiating light incident on said display element;
a second optical guide plate having a longitudinal direction extending along a widthwise direction of and at an end of said main optical guide plate, said second optical guide plate having a longitudinal length no longer than 100 mm, having a first end surface facing said main optical guide plate, and a second end surface, the second end surface including a plurality of prism-shaped grooves extending in a depth direction and lying along the longitudinal direction;
a point light source at a longitudinal end of said second optical guide plate; and
a reflective film coating a surface of said grooves.
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22. A front light arranged in front of a display device, comprising:
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a main optical guide plate;
a second optical guide plate having a longitudinal direction extending along a widthwise direction of and at an end of said main optical guide plate, said second optical guide plate having a longitudinal direction no longer than 100 mm, having a first end surface facing said main optical guide plate, and a second end surface, the second end surface including a plurality of prism-shaped grooves extending in a depth direction and lying along the longitudinal direction;
a point light source at a longitudinal end of said second optical guide plate; and
a reflective film coating a surface of said grooves.
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Specification