Polarizing back-lighting system for direct view liquid crystal displays
First Claim
1. A polarizing light source for providing polarized illumination over a two-dimensional surface, comprising:
- a slab-like light guide having an entrance face at one end thereof for admitting unpolarized light from a linear source, a planar front face for emitting polarized light, a planar back face, and an end face;
a polarizing device on said back face for reflecting light of a first polarization and transmitting light of a second polarization at non-normal angles of incidence, said reflected light being directed in said light guide to said end face;
a reflective arrangement under said polarizing device for returning said transmitted second polarized light to said light guide in a direction substantially normal to said polarizing device such that it passes unaffected through said polarizing device for exit through said front face; and
a polarization converter on said end face for changing the polarization of said reflected light of said first polarization into light of said second polarization and directing it into said reflective arrangement through said polarizing device as light of said second polarization for return to said light guide through said polarizing device in a direction substantially normal to said polarizing device such that it passes unaffected through said polarizing device from said reflective arrangement for exit through said front face.
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Accused Products
Abstract
A polarizing light source for providing polarized illumination over a two-dimensional surface has a slab-like light guide with an entrance face at one end thereof for admitting unpolarized light from a linear source, a planar front face for emitting polarized light, a planar back face, and an end face. A polarizing device is located on said back face for reflecting light of a first polarization and transmitting light of a second polarization at non-normal angles of incidence. The reflected light is directed in the light guide to the end face. A reflective arrangement under the polarizing device returns the transmitted light to the light guide in a direction substantially normal to the polarizing device such that it passes unaffected through the polarizing device for exit through the front face. A polarization converter on the end face changes the polarization of the reflected light and directs it into the reflective arrangement through the polarizing device as light of the second polarization for return to the light guide through the polarizing device in a direction substantially normal to the polarizing device such that it passes unaffected through the polarizing device from the reflective arrangement for exit through said front face.
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Citations
31 Claims
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1. A polarizing light source for providing polarized illumination over a two-dimensional surface, comprising:
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a slab-like light guide having an entrance face at one end thereof for admitting unpolarized light from a linear source, a planar front face for emitting polarized light, a planar back face, and an end face;
a polarizing device on said back face for reflecting light of a first polarization and transmitting light of a second polarization at non-normal angles of incidence, said reflected light being directed in said light guide to said end face;
a reflective arrangement under said polarizing device for returning said transmitted second polarized light to said light guide in a direction substantially normal to said polarizing device such that it passes unaffected through said polarizing device for exit through said front face; and
a polarization converter on said end face for changing the polarization of said reflected light of said first polarization into light of said second polarization and directing it into said reflective arrangement through said polarizing device as light of said second polarization for return to said light guide through said polarizing device in a direction substantially normal to said polarizing device such that it passes unaffected through said polarizing device from said reflective arrangement for exit through said front face. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of providing polarized illumination over a two-dimensional surface, comprising the steps of:
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directing light from a linear source through an entrance face into a slab-like light guide having a planar front face for emitting polarized light, a planar back face, and an end face;
directing said light in said light guide at non-normal angles of incidence to a polarizing device on said back face for reflecting light of a first polarization and transmitting light of a second polarization such that said reflected light is directed in said light guide to said end face;
returning said transmitted light to said light guide in a direction substantially normal to said polarizing device such that it passes unaffected through said polarizing device for exit through said front face; and
changing the polarization of said reflected light of said first polarization striking said end face and directing the light with changed polarization through said polarizing device at a non-normal angle of incidence for return into said light guide through said polarizing device in a direction substantially normal to said polarizing device such that said light with changed polarization passes unaffected through said polarizing device for exit through said front face. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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21. A liquid crystal display comprising:
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an addressable liquid crystal array;
a polarizing layer in front of said liquid crystal array;
a linear light source;
a slab-like light guide having an entrance face at one end thereof for admitting unpolarized light from said linear light source, a planar front face for emitting polarized light toward said addressable liquid crystal array, a planar back face, and an end face;
a polarizing device on said back face for reflecting light of a first polarization and transmitting light of a second polarization at non-normal angles of incidence, said reflected light being directed in said light guide to said end face;
a reflective arrangement under said polarizing device for returning said transmitted light to said light guide in a direction substantially normal to said polarizing device such that it passes unaffected through said polarizing device for exit through said front face toward said addressable liquid crystal array; and
a polarization converter on said end face for changing the polarization of said reflected light and directing it into said reflective arrangement through said polarizing device as light of said second polarization for return to said light guide through said polarizing device in a direction substantially normal to said polarizing device such that it passes unaffected through said polarizing device from said reflective arrangement for exit through said front face addressable liquid crystal array. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A polarizing light source for providing polarized illumination, comprising:
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a light guide having an entrance face at one end thereof for admitting unpolarized light, a planar front face for emitting polarized light, a planar back face, and an end face;
a polarizing device on said back face for reflecting light of a first polarization and transmitting light of a second polarization at non-normal angles of incidence, said reflected light being directed in said light guide to said end face;
a reflective arrangement under said polarizing device for returning said transmitted second polarized light to said light guide in a direction substantially normal to said polarizing device such that it passes unaffected through said polarizing device for exit through said front face; and
a polarization converter on said end face for changing the polarization of said reflected light of said first polarization into light of said second polarization and directing it into said reflective arrangement through said polarizing device as light of said second polarization for return to said light guide through said polarizing device in a direction substantially normal to said polarizing device such that it passes unaffected through said polarizing device from said reflective arrangement for exit through said front face.
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Specification