Abstract: A projector includes: a projection unit that projects projection light toward an illuminated surface; a housing that houses the projection unit and has an opening that allows the projection light to exit outward; and a cover portion that blocks the opening and transmits the projection light, wherein a plurality of areas is set in the cover portion relative to the projection unit, and a process of changing the reflectance of the light-incident surface of the cover portion at which the projection light is reflected is performed on each of the areas.

Abstract: A projection optical system includes: a refracting optical section composed mainly of a plurality of lenses disposed in order from a reducing side, and having positive power; a first reflecting optical section having a concave reflecting optical surface; and a second reflecting optical section having a convex reflecting optical surface, wherein the projection optical system satisfies the following conditional expression, denoting a focal length of a total system combining the refracting optical section, the first reflecting optical section, and the second reflecting optical section as F, and a focal length of the refracting optical section as FL: 0.2<F/FL<0.5??(1).

Abstract: In a projection optical system comprising: two lens groups, and a curved plane mirror, wherein the projection optical system including two story structure, and having bend means for bending at least two times the light incident from an electro-optic modulator.

Abstract: In a projection optical system comprising: two lens groups, and a curved plane mirror, wherein the projection optical system including two story structure, and having bend means for bending at least two times the light incident from an electro-optic modulator.

Abstract: In a projection optical system comprising: two lens groups, and a curved plane mirror, wherein the projection optical system including two story structure, and having bend means for bending at least two times the light incident from an electro-optic modulator.

Abstract: A projection type image display device comprising: a projection optical system having a first refracting optical section having a plurality of lenses, a reflecting optical section having at least one concave reflecting surfacer and a second refracting optical section in order from a reduction side; and an image forming optical section disposed on an anterior stage of a light path as the reduction side of the projection optical system, wherein the second refracting optical section has an exit lens having either: (1) a roughly constant thickness and disposed in a posterior stage of the light path from an exit pupil position at which a principal ray reflected by the reflecting surface and proceeding towards the maximum field angle and the optical axis of the reflecting optical section intersect with each other, and an optical surface of a magnification side of the exit lens has a shape convex towards the magnification side; or (2) a roughly constant thickness and disposed between the reflecting optical section

Abstract: A projection optical system includes: a refracting optical section composed mainly of a plurality of lenses disposed in order from a reducing side, and having positive power; a first reflecting optical section having a concave reflecting optical surface; and a second reflecting optical section having a convex reflecting optical surface, wherein the projection optical system satisfies the following conditional expression, denoting a focal length of a total system combining the refracting optical section, the first reflecting optical section, and the second reflecting optical section as F, and a focal length of the refracting optical section as FL: 0.2<F/FL<0.5??(1).

Abstract: A projection optical system includes: a refracting optical section composed mainly of a plurality of lenses disposed in order from a reducing side, and having positive power; a first reflecting optical section having a concave reflecting optical surface; and a second reflecting optical section having a convex reflecting optical surface, wherein the projection optical system satisfies the following conditional expression, denoting a focal length of a total system combining the refracting optical section, the first reflecting optical section, and the second reflecting optical section as F, and a focal length of the refracting optical section as FL: 0.2<F/FL<0.5??(1).

Abstract: A projection zoom lens includes in order from an enlargement side: a first lens group with negative power; a second lens group with positive power; a third lens group with positive power; a fourth lens group with positive power; and a fifth lens group with positive power, wherein the first and fifth lens groups are fixed and the second, third, and fourth lens groups move when zooming from a wide angle side to a telescopic side, the second lens group includes only a positive lens which is convex toward the enlargement side, and assuming that the focal length at a wide angle end of a whole system including the first to fifth lens groups is F and the focal length of the second lens group is F2, the following conditional expression (1) is satisfied: 0.05<F/F2<0.23??(1).

Abstract: A projection optical system includes: a refracting optical section composed mainly of a plurality of lenses disposed in order from a reducing side, and having positive power; a first reflecting optical section having a concave reflecting optical surface; and a second reflecting optical section having a convex reflecting optical surface, wherein the projection optical system satisfies the following conditional expression, denoting a focal length of a total system combining the refracting optical section, the first reflecting optical section, and the second reflecting optical section as F, and a focal length of the refracting optical section as FL: 0.2<F/FL<0.5??(1).

Abstract: A projection zoom lens includes in order from an enlargement side: a first lens group with negative power; a second lens group with positive power; a third lens group with positive power; a fourth lens group with positive power; and a fifth lens group with positive power, wherein the first and fifth lens groups are fixed and the second, third, and fourth lens groups move when zooming from a wide angle side to a telescopic side, the second lens group includes only a positive lens which is convex toward the enlargement side, and assuming that the focal length at a wide angle end of a whole system including the first to fifth lens groups is F and the focal length of the second lens group is F2, the following conditional expression (1) is satisfied: 0.05<F/F2<0.23??(1).

Abstract: A projector includes: a projection unit that projects projection light toward an illuminated surface; a housing that houses the projection unit and has an opening that allows the projection light to exit outward; and a cover portion that blocks the opening and transmits the projection light, wherein a plurality of areas is set in the cover portion relative to the projection unit, and a process of changing the reflectance of the light-incident surface of the cover portion at which the projection light is reflected is performed on each of the areas.

Abstract: A zoom lens includes a first lens group having negative power, a second lens group having positive power, a third lens group having positive power, and a fourth lens group having positive power, disposed in this order from the enlargement side to form the entire structure. At the time of zooming from the wide angle side to the telephoto side, the first lens group shifts from the enlargement side to the reduction side and the second and third lens groups shift from the reduction side to the enlargement side and the fourth lens group is fixed. The overall length of the zoom lens becomes the maximum at the wide angle end.

Abstract: In a projection optical system comprising: two lens groups, and a curved plane mirror, wherein the projection optical system including two story structure, and having bend means for bending at least two times the light incident from an electro-optic modulator.

Abstract: A projector includes a screen; a reflection unit having at least one curved surface mirror disposed on the projection side of the screen; a bending mirror disposed before the reflection unit on the optical path and disposed on either the non-projection side of the screen or on an extension plane of the screen; a refraction unit disposed before the reflection unit on the optical path and having at least a part disposed on either the non-projection side of the screen or on the extension plane of the screen; and an image forming unit disposed before the refraction unit on the optical path and disposed on the non-projection side of the screen.

Abstract: A projection type image display device comprising: a projection optical system having a first refracting optical section having a plurality of lenses, a reflecting optical section having at least one concave reflecting surfacer and a second refracting optical section in order from a reduction side; and an image forming optical section disposed on an anterior stage of a light path as the reduction side of the projection optical system, wherein the second refracting optical section has an exit lens having either: (1) a roughly constant thickness and disposed in a posterior stage of the light path from an exit pupil position at which a principal ray reflected by the reflecting surface and proceeding towards the maximum field angle and the optical axis of the reflecting optical section intersect with each other, and an optical surface of a magnification side of the exit lens has a shape convex towards the magnification side; or (2) a roughly constant thickness and disposed between the reflecting optical section

Abstract: A zoom lens includes a first lens group having negative power, a second lens group having positive power, a third lens group having positive power, and a fourth lens group having positive power, disposed in this order from the enlargement side to form the entire structure. At the time of zooming from the wide angle side to the telephoto side, the first lens group shifts from the enlargement side to the reduction side and the second and third lens groups shift from the reduction side to the enlargement side and the fourth lens group is fixed. The overall length of the zoom lens becomes the maximum at the wide angle end.

Abstract: An imaging optical system includes an aperture stop, a positive first lens group, and a positive or negative second lens group. The first lens group includes a positive first lens element and a negative second lens element. The first lens element is provided with an aspherical surface on the object-side surface thereof. The aspherical surface is formed so that the higher a height from the optical axis in a radial direction becomes the more an aspherical surface at the height is displaced toward the object, compared with a paraxial spherical surface. The second lens group includes a meniscus third lens element. The meniscus third lens element is provided with an aspherical surface on each lens surface thereof, and has the convex surface facing toward the object in the vicinity of the optical axis.

Abstract: An imaging optical system includes an aperture stop, a positive first lens group, and a positive or negative second lens group. The first lens group includes a positive first lens element and a negative second lens element. The first lens element is provided with an aspherical surface on the object-side surface thereof. The aspherical surface is formed so that the higher a height from the optical axis in a radial direction becomes the more an aspherical surface at the height is displaced toward the object, compared with a paraxial spherical surface. The second lens group includes a meniscus third lens element. The meniscus third lens element is provided with an aspherical surface on each lens surface thereof, and has the convex surface facing toward the object in the vicinity of the optical axis. The imaging optical system and the positive first lens element of the positive first lens group satisfy the following conditions: 0.6<|f1/f2|<1.0 . . . (1); 1.0<f12/f<1.6 . . . (2); 0.301?|R2/f|<0.7 .

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group. The negative first lens group includes a negative meniscus lens element having the convex surface facing toward the object, and the positive third lens group includes a positive biconvex lens element. Upon zooming, at least the negative first lens group and the positive second lens group are moved. A diaphragm is provided on the object side of the positive second lens group, and moves integrally therewith. The zoom lens system satisfies the following conditions: 0.25<R1/D1<0.55 . . . (1); 0.25<f2/TL<0.45 . . .