Patent ID: 8308301

Claim:
An optical unit comprising: a light source that emits light to be projected onto a screen; one or a plurality of optical elements that control(s) a spread of a beam of light from the light source to the screen; a combining element that combines the light emitted from the light source; and a scanning element; wherein the light source outputs an optical beam that will generate an elliptically shaped beam spot on the screen, the beam spot having a major axis substantially perpendicular to a scanning direction; and wherein the optical unit satisfies a relational expression of B= 2 f tan θ+ a≧S scan/ n scan≧φ sin γ, or B= 2 f tan θ+ a≧ 1.5 S scan/ n scan≧φ sin γ where a horizontal spot size of the beam on an exit surface of each optical element is defined as B (mm); a size of the beam spot in the scanning direction on the screen, as φ (mm); an angle formed between the scanning direction and the major axis of the spot, as γ (°); a distance from a light-emitting point of the light source to the optical element, as “f” (mm); an angle formed by the spread direction of the light emitted from the light source with an optical axis, as θ (°); a size of the light-emitting point in a direction parallel to the scanning direction, as “a” (mm); a size of the screen in the scanning direction, as Sscan (mm); and the number of pixels in a scan line in the scanning direction, as “nscan”.