Projection type display apparatus with color optimized anti-reflection films
First Claim
Patent Images
1. A projection type display apparatus for projecting a plurality of images of primary colors formed by a plurality of reflection type image forming elements to thereby form a colored image, characterized in that a plurality of anti-reflection films are provided, andwherein each anti-reflection film:
- (a) is substantially optimized or optimized for the corresponding primary color;
(b) is formed on a surface of a color separating and combining prism through which light of said corresponding primary color passes;
(c) is formed of two kinds of materials;
(d) has a layer of high refractive index, a layer of low refractive index and a layer of intermediate refractive index, and said layer of intermediate refractive index is constructed of equivalent film of said layer of high refractive index and said layer of low refractive index; and
(d) has one of the following configurations;
(i) substrate-λ
/4 (intermediate refractivity layer)-λ
/4 (high refractivity layer)-λ
/4 (low refractivity layer)-air;
(ii) substrate-λ
/2 (intermediate refractivity layer)-λ
/2 (high refractivity layer)-λ
/4 t(low refractivity layer)-air;
or(iii) substrate-3λ
/4 (intermediate refractivity layer)-λ
/2 (high refractivity layer)-λ
/4 (low refractivity layer)-air.
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Accused Products
Abstract
In a reflection type liquid crystal projector, anti-reflection film optimized for the corresponding color (wavelength band) is formed on each of the light passing surfaces of a cross dichroic prism which are opposed to liquid crystal panels of respective colors and the reflectance of each anti-reflection film is made sufficiently small to thereby enhance the contrast of a colored image projected onto a screen by a projection lens.
26 Citations
30 Claims
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1. A projection type display apparatus for projecting a plurality of images of primary colors formed by a plurality of reflection type image forming elements to thereby form a colored image, characterized in that a plurality of anti-reflection films are provided, and
wherein each anti-reflection film: -
(a) is substantially optimized or optimized for the corresponding primary color; (b) is formed on a surface of a color separating and combining prism through which light of said corresponding primary color passes; (c) is formed of two kinds of materials; (d) has a layer of high refractive index, a layer of low refractive index and a layer of intermediate refractive index, and said layer of intermediate refractive index is constructed of equivalent film of said layer of high refractive index and said layer of low refractive index; and (d) has one of the following configurations; (i) substrate-λ
/4 (intermediate refractivity layer)-λ
/4 (high refractivity layer)-λ
/4 (low refractivity layer)-air;(ii) substrate-λ
/2 (intermediate refractivity layer)-λ
/2 (high refractivity layer)-λ
/4 t(low refractivity layer)-air;
or(iii) substrate-3λ
/4 (intermediate refractivity layer)-λ
/2 (high refractivity layer)-λ
/4 (low refractivity layer)-air. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A projection type display apparatus for superposing a plurality of images of primary colors upon one another to thereby form a colored image, comprising:
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a plurality of optical elements each of which includes at least one of; (a) an element of a color-combining prism passing light of one of said primary colors; (b) an element of a color-separating prism passing light of one of said primary colors; and (c) a lens passing light of one of said primary colors; and a plurality of anti-reflection films wherein each of said anti-reflection films; (a) is formed on one of said plurality of optical elements, (b) is optimized or substantially optimized for a corresponding primary color, (c) is formed of two kinds of materials; (d) has a layer of high refractive index, a layer of low refractive index and a layer of intermediate refractive index, and said layer of intermediate refractive index is constructed of equivalent film of said layer of high refractive index and said layer of low refractive index; and (e) has one of the following configurations; (i) substrate-λ
/4 (intermediate refractivity layer)-λ
/4 (high refractivity layer)-λ
/4 (low refractivity layer)-air;(ii) substrate-λ
/2 (intermediate refractivity layer)-λ
/2 (high refractivity layer)-λ
/4 t(low refractivity layer)-air;
or(iii) substrate-3λ
/4 (intermediate refractivity layer)-λ
/2 (high refractivity layer)-λ
/4 (low refractivity layer)-air. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A projection type display apparatus for projecting a plurality of images of primary colors formed by a plurality of image forming elements to thereby form a colored image, comprising:
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a light source; separating means for separating light from said light source into said primary colors of light and for directing said primary colors of light to said image forming elements; combining means for combining said plurality of images of primary colors; and projecting means for projecting said combined plurality of images of primary colors, characterized in that an anti-reflection film substantially optimized or optimized for a corresponding primary color is formed on each of the surfaces of optical elements of said separating means and said combining means, wherein each of said anti-reflection films; (a) is formed of two kinds of materials; (b) has a layer of high refractive index, a layer of low refractive index, and a layer of intermediate refractive index, and said layer of intermediate refractive index is constructed of equivalent film of said layer of high refractive index and said layer of low refractive index; and (c) has one of the following configurations; (i) substrate-λ
/4 (intermediate refractivity layer)-λ
/4 (high refractivity layer)-λ
/4 (low refractivity layer)-air;(ii) substrate-λ
/2 (intermediate refractivity layer)-λ
/2 thickness (high refractivity layer)-λ
/4 t(low refractivity layer)-air;
or(iii) substrate-3λ
/4 (intermediate refractivity layer)-λ
/2 (high refractivity layer)-λ
/4 (low refractivity layer)-air. - View Dependent Claims (28, 29, 30)
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Specification
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Current AssigneeCanon Kabushiki Kaisha (Canon Inc.)
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Original AssigneeCanon Kabushiki Kaisha (Canon Inc.)
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InventorsKoyama, Osamu
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Primary Examiner(s)Sikes, William L.
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Assistant Examiner(s)CHOWDHURY, TARIFUR RASHID
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Application NumberUS08/895,352Time in Patent Office979 DaysField of Search349/137, 349/5, 349/8, 349/9, 349/62, 359/580, 359/581US Class Current349/8CPC Class CodesG02B 1/115 MultilayersG02B 27/1026 for use with reflective spa...G02B 27/1046 for use with transmissive s...G02B 27/142 Coating structures, e.g. th...G02B 27/145 having sequential partially...G02B 27/149 using crossed beamsplitting...H04N 9/3105 for displaying all colours ...
