Liquid crystal projector

• US 7,659,946 B2
• Filed: 06/13/2005
• Issued: 02/09/2010
• Est. Priority Date: 06/29/2004
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Inukai, Hitoshi, Yano, Tomoya, Shirasaka, Yasuhiro
• Primary Examiner(s): Pak; Sung H
• Application Number:
  US11/571,368
• Publication Number:
  US 20080043158A1
• Time in Patent Office: 1,702 Days
• Field of Search: None
• US Class Current: 349/9
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/1393 the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells G02F1/1396, G02F1/141 take precedence
• CPC Class Codes: G02F 2203/01 transmissive
• CPC Class Codes: G02F 2413/01 Number of plates being 1
• CPC Class Codes: G02F 2413/10 with refractive index ellipsoid inclined, or tilted, relative to the LC-layer surface O plate
• CPC Class Codes: G03B 21/2073 Polarisers in the lamp house peculiar to electronic spatial light modulators H04N9/3197
• CPC Class Codes: G03B 21/28 Reflectors in projection beam in illumination beam G03B21/2066
• CPC Class Codes: H04N 9/3105 for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators simultaneous projection in colour photography G03B33/10; beam splitting or combining systems per se G02B27/10
• CPC Class Codes: H04N 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

Disclosed is a transmissive liquid crystal projector carrying a vertical alignment liquid crystal device. The liquid crystal projector includes a liquid crystal panel (25), on the light incident side and on the light radiating side of which a light incident side polarizing plate (24) and a light radiating side light polarizing plate (26) are arranged, respectively. A first polarized light component in a light beam collected by an illuminating optical system is transmitted through the light incident side polarizing plate (24) and routed to the liquid crystal panel (25). An optical anisotropic device (45), tilted by a preset angle correlated with the direction of alignment of liquid crystal molecules in the liquid crystal panel (25), that is, a pre-tilt angle, is arranged between the light incident side polarizing plate (24) and the liquid crystal panel (25) or between the light radiating side light polarizing plate (26) and the liquid crystal panel (25). By so doing, a high contrast ratio may be maintained, while transmittance of the liquid crystal panel may be improved.

Claims

1. A liquid crystal projector including a light source, an illuminating optical system for condensing a light beam, radiated from said light source, on a desired light path, a liquid crystal device for light modulating the light beam, collected by said illuminating optical system, by liquid crystal molecules arranged in a state of vertical alignment, and a projection lens for projecting said light beam, light modulated by said liquid crystal device, to an enlarged scale, said liquid crystal projector comprising:

light polarization controlling means including a first light polarizing plate and a second light polarizing plate, arranged on a light incident side and on a light radiating side of said liquid crystal device, respectively;

said first light polarizing plate transmitting a first polarized light component in said light beam collected by said illuminating optical system and routing the transmitted first polarized light component to said liquid crystal device;

said second light polarizing plate transmitting a second polarized light component in said light beam radiated from said liquid crystal device and routing the transmitted second polarized light component to said projection lens; and

phase difference means formed by an optical anisotropic device arranged between said first light polarizing plate and said liquid crystal device or between said second light polarizing plate and said liquid crystal device;

said optical anisotropic device of said phase difference means being tilted by an angle from a plane parallel to the liquid crystal device and with an optical axis of the optical anisotropic device as the center of rotation, wherein the angle is correlated with the direction of alignment of liquid crystal molecules in said liquid crystal device.

2. The liquid crystal projector according to claim 1 wherein said optical anisotropic device of said phase difference means is tilted by an angle which is correlated with the refractive index of a medium from said liquid crystal device up to said optical anisotropic device and with the refractive index of said liquid crystal device.

3. The liquid crystal projector according to claim 1 wherein liquid crystal molecules in said liquid crystal device are of homeotropic alignment.

4. The liquid crystal projector according to claim 1 wherein said optical anisotropic device of said phase difference means is tilted by an angle about the direction perpendicular to the direction of alignment of liquid crystal molecules in said liquid crystal device.

5. The liquid crystal projector according to claim 1 further comprising:

means for adjusting the angle of tilt of said optical anisotropic device of said phase difference means.

6. The liquid crystal projector according to claim 5, wherein the adjusting means includes a compensation plate tilt mechanism for supporting the optical anisotropic device and changing the angle of rotation of the optical anisotropic device from the plane parallel to the liquid crystal device.

7. The liquid crystal projector according to claim 6, wherein the compensation plate tilt mechanism includes a support block defining an opening;

a rotary ring rotatably attached to the support block within the opening;

an optical compensation plate mounting unit that supports the optical anisotropic device; and

a tilt shaft connecting the mounting unit to the rotary ring for rotating the mounting unit perpendicular to the axis of rotation of the rotary ring.