Liquid crystal light valve apparatus with a pair of non-parallel phase difference plates

A liquid crystal light valve apparatus of projection type comprising:

• a light source for emitting an illumination light,
• a liquid crystal light valve apparatus for modulating said illumination light and forming an optical image,
• a projection lens for projecting said optical image on a screen, and
• a primary illumination ray defined as a main light having a predetermined wavelength which is representative of said illumination light, and said primary illumination ray emitted from said light source passes adjacent to the center of gravity of an effective display area of said liquid crystal light valve apparatus and adjacent to the center of gravity of an entrance pupil of said projection lens and is projected on said screen, and
• said liquid crystal light valve apparatus comprises
• an incident side polarizing means for transmitting a linearly polarized light having a first polarization axis in a first direction,
• a liquid crystal cell comprising incident side and outgoing side transparent substrates having twisted nematic liquid crystal with a twist angle of about 90 degrees therebetween,
• an outgoing side linear polarizing means for transmitting a linearly polarized light having a second polarization axis in a second predetermined direction,
• first and second phase difference means each having a function similar to a positive or negative uniaxial crystal, both disposed between said incident side polarizing means and said liquid crystal cell or between said liquid crystal cell and said outgoing side polarizing means,
• the direction of the polarization axis of said incident side polarizing means being either parallel or perpendicular to the major axis direction of liquid crystal moleculars contacting said incident side transparent substrate,
• said first and second polarizing axes, an optical axis of said first phase difference means and an optical axis of said second phase difference means having first, second, third and fourth projections, respectively in a plane perpendicular to said primary illumination ray,
• said first and second projections and said third and fourth projections being substantially orthogonal and said first and third projections forming an angle of about 45 degrees,
• first and second angles .phi..sub.1 and .phi..sub.2 defined as the angles between said optical axes of said first and second phase difference means respectively, and a plane perpendicular to said primary illumination ray,
• said first phase difference means and said second phase difference means giving phase differences which are equal in magnitude and opposite in sign to said primary illumination ray when said first and second angles each equal zero degrees,
• one of said first angle and said second angle being predetermined in a manner such that light intensity of said primary illumination ray passing through said outgoing side polarizing means becomes a minimum when the liquid crystal cell is in the darkest state.

A liquid crystal light valve apparatus of a projection type comprising:

• a light source for emitting illumination light including color components of three primary colors,
• color separating means for separating said illumination light emitted from said light source to illumination lights of three primary colors,
• three liquid crystal light valve apparatuses for forming three optical images corresponding to said three primary colors by modulating said illumination lights of said three primary colors emitted from said color separating means,
• color combining means for combining said illumination lights of said three primary colors emitted from said three liquid crystal light valve apparatus to one illumination light,
• a projection lens for projecting said illumination light emitted from said color combining means on a screen, and
• a primary illumination ray defined as a main light having a predetermined wavelength which is representative of said illumination ray corresponding to said three liquid crystal light valve apparatuses,
• said three liquid crystal light valve apparatuses each comprise
• an incident side polarizing means for transmitting a linearly polarized light having a first polarization axis in a first direction,
• a liquid crystal cell comprising incident side and outgoing side transparent substrates having twisted nematic liquid crystal with a twist angle of about 90 degrees therebetween,
• an outgoing side linear polarizing means for transmitting a linearly polarized light having a second polarization axis in a second predetermined direction,
• first and second phase difference means each having a function similar to a positive or negative uniaxial crystal, both disposed between said incident side polarizing means and said liquid crystal display cell or between said liquid crystal display cell and said outgoing side polarizing means,
• the direction of the polarization axis of said incident side polarizing means being either parallel or perpendicular to the major axis direction of liquid crystal moleculars contacting said incident side transparent substrate,
• said first and second polarizing axes, an optical axis of said first phase difference means and an optical axis of said second phase difference means having first, second, third and fourth projections, respectively in a plane perpendicular to said primary illumination ray,
• said first and second projections and said third and fourth projections being substantially orthogonal and said first and third projections forming an angle of about 45 degrees,
• first and second angles .phi..sub.1 and .phi..sub.2 defined as the angles between said optical axes of said first and second phase difference means, respectively and a plane perpendicular to said primary illumination ray,
• said first phase difference means and said second phase difference means giving phase differences which are equal in magnitude and opposite in sign to said primary illumination ray when said first and second angles each equal zero degrees,
• one of said first angle and said second angle being predetermined in a manner such that light intensity of said primary illumination ray passing through said outgoing said polarizing means becomes a minimum when the liquid crystal cell is in a darkest state.

A liquid crystal light valve apparatus of a projection type comprising:

• a light source for emitting an illumination light having means for moving said light source in an arbitrary direction,
• a liquid crystal valve apparatus for forming optical images by modulating said illumination light,
• a projection lens for projecting said optical image on a screen,
• means for parallelly moving said projection lens in the direction perpendicular to said optical axis, and
• a primary illumination ray defined as a light which passes in the vicinity of the center of gravity of said effective display area of said liquid crystal light valve apparatus and applied to the center of gravity of an entrance pupil of said projection lens,
• said liquid crystal light valve apparatus comprises
• an incident side polarizing means for transmitting a linearly polarized light having a first polarization axis in a first direction,
• a liquid crystal cell comprising incident and outgoing side transparent substrates having twisted nematic liquid crystal with a twist angle of about 90 degrees therebetween,
• an outgoing side linear polarizing means for transmitting a linearly polarized light having a second polarization axis in a second predetermined direction,
• first and second phase difference means each having a function similar to a positive or negative uniaxial crystal, both disposed between said incident side polarizing means and said liquid crystal cell or between said liquid crystal cell and said outgoing side polarizing means,
• the direction of the polarization axis of said incident said polarizing means being either parallel or perpendicular to the major axis direction of liquid crystal moleculars contacting said incident side transparent substrate,
• said first and second polarizing axes, an optical axis of said first phase difference means and an optical axis of said second phase difference means having first, second, third and fourth projections respectively in a plane perpendicular to said primary illumination ray,
• said first and second projections and said third and fourth projections being substantially orthogonal and said first and third projections forming an angle of about 45 degrees,
• first and second angles .phi..sub.1 and .phi..sub.2 defined as the angles between said optical axes of said first and second phase difference means respectively and a plane perpendicular to said primary illumination ray,
• said first phase difference means and said second phase difference means giving phase differences which are equal in magnitude and opposite in sign to said primary illumination ray when said first and second angles each equal zero,
• one of said first angle and said second angle being predetermined in a manner such that light intensity of said primary illumination ray passing said outgoing side polarizing means becomes a minimum when the liquid crystal cell is in a darkest state.