Color-separating and -recombining optical system and projection display using the same

Claim 2

A color-separating and -recombining optical system comprising: cubic- or square column-like first to fourth polarization beam splitters having polarization-splitting planes intersecting each other like a character-“X”; and wavelength-selective polarizing converters each for rotating the plane of polarization of a specific-color light component by 90 degrees, one of the converters being placed at a light-incident side of the first splitter, another of the converters being placed at a light-emitting side of the fourth splitter, the first and the fourth splitters being provided at a light-incident side and a light-emitting side, respectively, of the optical system, the first and the fourth splitters being arranged as diagonally opposing each other, and the remaining converters being placed between at least two inner facing planes of the first to the fourth splitters, wherein at least the remaining converters and three of the first to the fourth splitters are joined to form an optical joint component with a gap located between the remaining one splitter and the optical joint component.

Claim 3

The color-separating and -recombining optical system according to claim 1 , wherein opto-elastic constants for the first to the fourth polarization beam splitters have a relationship Ki<Km and Ko in which Ki, Km and Ko denote the opto-elastic constants for the first splitter, the second and the third splitters and the fourth splitter, respectively.

Claim 4

The color-separating and -recombining optical system according to claim 1 , wherein opto-elastic constants for the first to the fourth polarization beam splitters have a relationship Ki and Km<Ko in which Ki, Km and Ko denote the opto-elastic constants for the first splitter, the second and the third splitters and the fourth splitter, respectively.

Claim 5

The color-separating and -recombining optical system according to claim 1 , wherein opto-elastic constants for the first to the fourth polarization beam splitters have a relationship Ki<Km<Ko in which Ki, Km and Ko denote the opto-elastic constants for the first splitter, the second and the third splitters and the fourth splitter, respectively.

Claim 6

A color-separating and -recombining optical system comprising: cubic- or square column-like first to fourth polarization beam splitters having polarization-splitting planes intersecting each other like a character-“X”; and wavelength-selective polarizing converters each for rotating the plane of polarization of a specific-color light component by 90 degrees, one of the converters being placed at a light-incident side of the first splitter, another of the converters being placed at a light-emitting side of the fourth splitter, the first and the fourth splitters being provided at a light-incident side and a light-emitting side, respectively, of the optical system, the first and the fourth splitters being arranged as diagonally opposing each other, and the remaining converters being placed between at least two inner facing planes of the first to the fourth splitters, wherein opto-elastic constants for the first to the fourth splitters have a relationship Ki<Km and Ko, Ki and Km<Ko or Ki<Km<Ko in which Ki, Km and Ko denote the opto-elastic constants for the first splitter, the second and the third splitters and the fourth splitter, respectively.

Claim 7

A color-separating and -recombining optical system comprising: cubic- or square column-like first to fourth polarization beam splitters having polarization-splitting planes intersecting each other like a character-“X”; and wavelength-selective polarizing converters each for rotating the plane of polarization of a specific-color light component by 90 degrees, one of the converters being placed at a light-incident side of the first splitter, another of the converters being placed at a light-emitting side of the fourth splitter, the first and the fourth splitters being provided at a light-incident side and a light-emitting side, respectively, of the optical system, the first and the fourth splitters being arranged as diagonally opposing each other, and the remaining converters being placed between at least two inner facing planes of the first to the fourth splitters, wherein opto-elastic constants for the first to the fourth splitters have a relationship Ki<Km and Ko, Ki and Km<Ko or Ki<Km<Ko in which Ki, Km and Ko denote the opto-elastic constants for the first splitter, the second and the third splitters and the fourth splitter, respectively.

Claim 8

A projection display comprising: a light source for emitting unlinearly-polarized light; a first polarizer to allow only a first specific-linearly-polarized light component of the unlinearly-polarized light to pass therethrough; a color-separating and -recombining optical system including cubic- or square column-like first to fourth polarization beam splitters having polarization-splitting planes intersecting each other like a character-“X”, the first splitter being provided as facing the first polarizer, and wavelength-selective polarizing converters each for rotating the plane of polarization of a specific-color light component by 90 degrees, one of the converters being placed at a light-incident side of the first splitter, another of the converters being placed at a light-emitting side of the fourth splitter, the first and the fourth splitters being provided at a light-incident side and a light-emitting side, respectively, of the optical system, the first and the fourth splitters being arranged as diagonally opposing each other, and the remaining converters being placed between at least two inner facing planes of the first to the fourth splitters, wherein at least the remaining converters and three of the first to the fourth splitters are joined to form an optical joint component with a gap located between the remaining one splitter and the optical joint component; reflective spatial light modulators for light modulation in accordance with a video signal, provided outside the optical system, as facing each light-passing plane of the second and the third splitters, a second polarizer provided as facing a light-emitting side plane of the fourth splitter, to allow only a second specific-linearly-polarized light component emitted from the light-emitting side plane of the fourth splitter to pass therethrough; and a projection lens provided as facing the second polarizer, to receive the second specific-linearly-polarized light component for image projection.

Claim 9

A projection display comprising: a light source for emitting unlinearly-polarized light; a first polarizer to allow only a first specific-linearly-polarized light component of the unlinearly-polarized light to pass therethrough; a color-separating and -recombining optical system including cubic- or square column-like first to fourth polarization beam splitters having polarization-splitting planes intersecting each other like a character-“X”, the first splitter being provided as facing the first polarizer, and wavelength-selective polarizing converters each for rotating the plane of polarization of a specific-color light component by 90 degrees, one of the converters being placed at a light-incident side of the first splitter, another of the converters being placed at a light-emitting side of the fourth splitter, the first and the fourth splitters being provided at a light-incident side and a light-emitting side, respectively, of the optical system, the first and the fourth splitters being arranged as diagonally opposing each other, and the remaining converters being placed between at least two inner facing planes of the first to the fourth splitters, wherein at least the remaining converters and three of the first to the fourth splitters are joined to form an optical joint component with a gap located between the remaining one splitter and the optical joint component; reflective spatial light modulators for light modulation in accordance with a video signal, provided outside the optical system, as facing each light-passing plane of the second and the third splitters, a second polarizer provided as facing a light-emitting side plane of the fourth splitter, to allow only a second specific-linearly-polarized light component emitted from the light-emitting side plane of the fourth splitter to pass therethrough; and a projection lens provided as facing the second polarizer, to receive the second specific-linearly-polarized light component for image projection.

Claim 10

A projection display comprising: a light source for emitting unlinearly-polarized light; a first polarizer to allow only a first specific-linearly-polarized light component of the unlinearly-polarized light to pass therethrough; a color-separating and -recombining optical system including cubic- or square column-like first to fourth polarization beam splitters having polarization-splitting planes intersecting each other like a character-“X”, the first splitter being provided as facing the first polarizer, and wavelength-selective polarizing converters each for rotating the plane of polarization of a specific-color light component by 90 degrees, one of the converters being placed at a light-incident side of the first splitter, another of the converters being placed at a light-emitting side of the fourth splitter, the first and the fourth splitters being provided at a light-incident side and a light-emitting side, respectively, of the optical system, the first and the fourth splitters being arranged as diagonally opposing each other, and the remaining converters being placed between at least two inner facing planes of the first to the fourth splitters, wherein opto-elastic constants for the first to the fourth splitters have a relationship Ki<Km and Ko, Ki and Km<Ko or Ki<Km <Ko in which Ki, Km and Ko denote the opto-elastic constants for the first splitter, the second and the third splitters and the fourth splitter, respectively; reflective spatial light modulators for light modulation in accordance with a video signal, provided outside the optical system, as facing each light-passing plane of the second and the third splitters, a second polarizer provided as facing a light-emitting side plane of the fourth splitter, to allow only a second specific-linearly-polarized light component emitted from the light-emitting side plane of the fourth splitter to pass therethrough; and a projection lens provided as facing the second polarizer, to receive the second specific-linearly-polarized light component for image projection.

Claim 11

A projection display comprising: a light source for emitting unlinearly-polarized light; a first polarizer to allow only a first specific-linearly-polarized light component of the unlinearly-polarized light to pass therethrough; a color-separating and -recombining optical system including cubic- or square column-like first to fourth polarization beam splitters having polarization-splitting planes intersecting each other like a character-“X”, the first splitter being provided as facing the first polarizer, and wavelength-selective polarizing converters each for rotating the plane of polarization of a specific-color light component by 90 degrees, one of the converters being placed at a light-incident side of the first splitter, another of the converters being placed at a light-emitting side of the fourth splitter, the first and the fourth splitters being provided at a light-incident side and a light-emitting side, respectively, of the optical system, the first and the fourth splitters being arranged as diagonally opposing each other, and the remaining converters being placed between at least two inner facing planes of the first to the fourth splitters, wherein opto-elastic constants for the first to the fourth splitters have a relationship Ki<Km and Ko, Ki and Km<Ko or Ki<Km <Ko in which Ki, Km and Ko denote the opto-elastic constants for the first splitter, the second and the third splitters and the fourth splitter, respectively; reflective spatial light modulators for light modulation in accordance with a video signal, provided outside the optical system, as facing each light-passing plane of the second and the third splitters, a second polarizer provided as facing a light-emitting side plane of the fourth splitter, to allow only a second specific-linearly-polarized light component emitted from the light-emitting side plane of the fourth splitter to pass therethrough; and a projection lens provided as facing the second polarizer, to receive the second specific-linearly-polarized light component for image projection.