Front illumination device and reflection-type liquid crystal display device incorporating same
First Claim
Patent Images
1. A front illumination device, comprising:
- a light source;
a first light-conducting body which guides light from said light source to an object to be illuminated, which is to be used by mounting in front of said object to be illuminated;
wherein said first light-conducting body is a polyhedron provided with a light-entry surface through which light from said light source enters, a first light exit surface through which light exits toward said object to be illuminated, and a second light exit surface opposite said first exit surface;
wherein said first and second light exit surfaces are provided so as to be substantially parallel;
wherein said light-entry surface is provided so as to incline with respect to a normal direction of said first light exit surface;
a light control means, provided between said light source and said light-entry surface, which limit spread of light from said light source; and
wherein the following inequality is satisfied,
space="preserve" listing-type="equation">arcsin((sin δ
)/n.sub.1)<
β
where β
is an angle formed by said light-entry surface and a normal direction of said first light exit surface, n1 is a refractive index of said first light-conducting body, and ±
δ
is an angle of spread of light limited by said light-control means.
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Abstract
A front-light, to be used by mounting on the front of a reflection-type LCD, etc., is provided with a light-conducting body having a light-entry surface, through which light enters from a light source, and a light exit surface, through which light is projected toward a liquid crystal cell; the light-entry surface being provided so as to incline with respect to the normal direction of the light exit surface.
147 Citations
24 Claims
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1. A front illumination device, comprising:
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a light source; a first light-conducting body which guides light from said light source to an object to be illuminated, which is to be used by mounting in front of said object to be illuminated; wherein said first light-conducting body is a polyhedron provided with a light-entry surface through which light from said light source enters, a first light exit surface through which light exits toward said object to be illuminated, and a second light exit surface opposite said first exit surface; wherein said first and second light exit surfaces are provided so as to be substantially parallel; wherein said light-entry surface is provided so as to incline with respect to a normal direction of said first light exit surface; a light control means, provided between said light source and said light-entry surface, which limit spread of light from said light source; and wherein the following inequality is satisfied,
space="preserve" listing-type="equation">arcsin((sin δ
)/n.sub.1)<
βwhere β
is an angle formed by said light-entry surface and a normal direction of said first light exit surface, n1 is a refractive index of said first light-conducting body, and ±
δ
is an angle of spread of light limited by said light-control means. - View Dependent Claims (2, 3, 4, 5)
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6. A front illumination device, comprising:
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a light source; a first light-conducting body which guides light from said light source to an object to be illuminated, which is to be used by mounting in front of said object to be illuminated; wherein said first light-conducting body is a polyhedron provided with a light-entry surface through which light from said light source enters, a first light exit surface through which light exits toward said object to be illuminated, and a second light exit surface opposite said first exit surface; wherein said first and second light exit surfaces are provided such that an interval therebetween grows smaller the greater a distance from said light-entry surface; wherein said light-entry surface is provided so as to incline with respect to a normal direction of said first light exit surface; a light control means, provided between said light source and said light-entry surface, which limit spread of light from said light source; and wherein the following inequality is satisfied,
space="preserve" listing-type="equation">arcsin((sin δ
/n.sub.1)<
β
+2αwhere α
is an angle of inclination of said second light exit surface with respect to said first light exit surface, β
is an angle formed by said light-entry surface and a normal direction of said first light exit surface, n1 is a refractive index of said first light-conducting body, ±
δ
is an angle of spread of light limited by said light-control means, and θ
c2 is a critical angle of said second light exit surface. - View Dependent Claims (7, 8, 9, 20)
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10. A front illumination device, comprising:
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a light source; a first light-conducting body which guides light from said light source to an object to be illuminated, which is to be used by mounting in front of said object to be illuminated; wherein said first light-conducting body is a polyhedron provided with a light-entry surface through which light from said light source enters, a first light exit surface through which light exits toward said object to be illuminated, and a second light exit surface opposite said first exit surface; wherein said first and second light exit surfaces are provided substantially parallel, or such that an interval therebetween grows smaller the greater a distance from said light-entry surface; wherein said light-entry surface is provided so as to incline with respect to a normal direction of said first light exit surface; a second light-conducting body provided outside said first light exit surface of said first light-conducting body; and said second light-conducting body transmitting light projected from said first light exit surface such that light exits said second light-conducting body in a direction closer to a normal direction of said first light exit surface than a direction in which light exits said first light exit surface. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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21. A reflection-type liquid crystal display device, comprising:
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a reflection-type liquid crystal element which has a reflective plate; a front illumination device provided on the front of said reflection-type liquid element; wherein a gap between said reflection-type liquid crystal element and said front illumination device is filled with a filler agent, which alleviates differences in refractive indices at optical interfaces between said reflection-type liquid crystal element and said front illumination device; and wherein the front illumination device includes; a light source, a first light-conducting body which guides light from said light source to an object to be illuminated, which is to be used by mounting in front of said object to be illuminated, wherein said first light-conducting body is a polyhedron provided with a light-entry surface through which light from said light source enters, a first light exit surface through which light exits toward said object to be illuminated, and a second light exit surface opposite said first exit surface, wherein said first and second light exit surfaces are provided substantially parallel, or such that an interval therebetween grows smaller the greater a distance from said light-entry surface, and wherein said light-entry surface is provided so as to incline with respect to a normal direction of said first light exit surface. - View Dependent Claims (22, 23, 24)
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Specification