Patent ID: 9581795
Date: 2017-02-28
CPC Classifications: G02B,G03B,H04N

Claim:
1. A projection-type video display device comprising: a lens group which is disposed in a light propagation direction with respect to a video display element and includes a plurality of lenses; a first free-form-surface lens which is disposed in the light propagation direction with respect to the lens group; a second free-form-surface lens which is disposed in the light propagation direction with respect to the first free-form-surface lens; and a free-form-surface mirror which reflects light emitted from the second free-form-surface lens to project the light on a screen in an inclined manner, wherein the lens group includes, in order from a side close to the video display element, a first lens which has positive refractive power and a bi-convex shape of which a small radius of curvature is oriented toward the side close to the video display element, a second lens which has an aspherical shape, a third lens which has positive refractive power and a bi-convex shape, a fourth lens which has negative refractive power and a bi-concave shape, a fifth lens which has positive refractive power and a bi-convex shape, a sixth lens which has positive refractive power and a bi-convex shape of which a small radius of curvature is oriented toward a magnification side, a seventh lens which has negative refractive power and an aspherical meniscus shape of which a convex surface is oriented toward a reduction side, an eighth lens which has negative refractive power and a bi-concave shape, a ninth lens which has positive refractive power and a bi-convex shape of which a small radius of curvature is oriented toward the magnification side, and a tenth lens which has negative refractive power and an aspherical meniscus shape of which a convex surface is oriented toward the magnification side, wherein the third, fourth, and fifth lenses constitute a cemented triplet lens, and wherein the first and second free-form-surface lenses have a meniscus lens shape of which a convex surface is oriented toward the magnification side.