US 6,601,958 B2Granted

Projector

AssigneeSeiko Epson Corporation

InventorYoshitaka Ito

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Abstract

The distance between reflection surfaces of a light guide is set in such a manner as to gradually decrease toward an exit end surface from an incidence end surface. Thus, the equation SY/SX<MY/MX is satisfied, where SX designates the arrangement intervals of light source images in the direction along the X-axis, SY denotes the arrangement intervals of the light source images in the direction along the Y-axis, MX designates the length of the incidence end surface of the light guide in the direction along the X-axis, and MY denotes the length of the incidence end surface of the light guide in the direction along the Y-axis. Thus, the polarization separation performance of a polarization beam splitter disposed before the reflection type liquid crystal device can be maintained at a relatively high level. Consequently, a bright projection image having a high contrast ratio can be obtained.

Claims14

Dependent claims

A projector, comprising:

an illumination device including a light beam dividing optical element, that divides a light beam into a plurality of sub light beams, and that forms a plurality of light source images from said plurality of the sub light beams;
an electro-optical device that modulates an illumination light beam emitted by said illumination device;
a projection lens that projects the light beam modulated by said electro-optical device;
and
a polarization separation film that selects a light beam of a predetermined polarization component included in said illumination light beam to emit the selected light beam of the predetermined polarization component to said electro-optical device, and that selects a light beam of a predetermined polarization component from the light beam modulated by said electro-optical device to emit the selected light beam to said projection lens,
said light beam dividing optical element being a rod-like light guide having an incidence end surface, an exit end surface, and at least four reflective surfaces, and satisfying:
SY/SX<MY/MX,
where:
MX is a length of said incidence end surface in the X-direction,
MY is a length of said incidence end surface in the Y-direction,
SX is a placement interval of said plurality of the light source images in the X-direction, and
SY is a placement interval of said plurality of the light source images in the Y-direction,
when:
an incident plane is a plane defined by a center axis of said illumination light beam and a normal to said polarization separation film,
a direction parallel to said incident plane and perpendicular to an illumination optical axis is an X-direction, and
a direction perpendicular to said incident plane is a Y-direction.

13 more elements

A projector, comprising:

an illumination device including a light beam dividing optical element, that divides a bundle of light beams into a plurality of sub light beams and that forms a plurality of light source images from said plurality of sub light beams;
an electro-optical device that modulates an illumination light beam emitted by said illumination device;
a projection lens that projects the light beam modulated by said electro-optical device;
and
a polarization separation film that selects a light beam of a predetermined polarization component included in the illumination light beam to emit the selected light beam of the predetermined polarization component to said electro-optical device, and that selects a light beam of a predetermined polarization component from the light beam modulated by said electro-optical device to emit the selected light beam to said projection lens,
said light beam dividing optical element being a lens array having a plurality of small lenses, and satisfying:
SY/SX<MY/MX,
where:
MX is a length of a contour of a small lens in the X-direction,
MY is a length of a contour of a small lens in the Y-direction,
SX is a placement interval of said plurality of the light source images in the X-direction, and
SY is a placement interval of said plurality of the light source images in the Y-direction,
when:
an incident plane is a plane defined by a center axis of said illumination light beam and a normal to said polarization separation film,
a direction parallel to said incident plane and perpendicular to an illumination optical axis is an X-direction, and
a direction perpendicular to said incident plane is a Y-direction.

13 more elements

Dependencies are inferred from the claim text.