Patent ID: 8459804

Claim:
A projection display device, comprising: an illumination optical unit configured to emit a light for illumination; an integrator configured to convert the light emitted from the illumination optical unit into a uniform light; an image projection unit configured to receive the uniform light emitted from the integrator and to project a light onto an external screen; a first reflection mirror configured to reflect the light emitted from the illumination optical unit to the integrator; a second reflection mirror configured to reflect corresponding light emerging from the integrator; and a third reflection mirror configured to reflect light reflected from the second reflection mirror to the image projection unit, wherein a first optical path is formed between the illumination optical unit and the first reflection mirror, wherein a second optical path is formed between the first and second reflection mirrors, wherein a third optical path is formed between the second reflection mirror and the third reflection mirror, wherein a fourth optical path is formed between the third reflection mirror and the image projection unit, wherein a fifth optical path is formed between the image projection unit and the external screen, wherein an angle between the first and second optical paths is a first acute angle and an angle between the second and third optical paths is a second acute angle, and wherein the third optical path is parallel to the first optical path, the fifth optical path is perpendicular to the first and third optical paths, and a light forward direction of the first optical path is the same as a light forward direction of the third optical path.