Abstract: A head-up display system of the present disclosure includes a display device that displays an image and a projection optical system that projects on the display member the image displayed on the display device. The projection optical system includes mirror ML that reflects a light beam toward the display member and mirror ML?1 that reflects the light beam toward mirror ML. Then, the projection optical system satisfies following condition (1): 0.01<|MLD/MLW|×|ML?1Z/ML?1W|??(1) where MLD is depth of mirror ML MLW is lateral dimension of mirror ML ML?1Z is maximum sag amount of mirror ML?1 ML?1W is lateral dimension of mirror ML?1. Such a configuration provides a head-up display system small in size that makes image distortion small in an entire viewpoint area of an observer.

Abstract: A head-up display includes a display device that displays an image toward a vertically downward direction, a first mirror that reflects the image to output reflected light toward a vertically upward direction, and a second mirror that reflects the reflected light from the first mirror to output reflected light toward a vertically upward direction. A vehicle includes the head-up display, and a windshield that reflects the reflected light emitted from the head-up display.

Abstract: A zoom lens system, in order from an object side to an image side, comprising: a first lens unit having positive optical power; a second lens unit having negative optical power; a third lens unit having positive optical power; a fourth lens unit having negative optical power; a fifth lens unit; and a sixth lens unit, wherein in zooming from a wide-angle limit to a telephoto limit at a time of image taking, the first lens unit, the second lens unit, the third lens unit, and the fourth lens unit move along an optical axis so that an interval between the third lens unit and the fourth lens unit at the telephoto limit is larger than that at the wide-angle limit, and wherein focusing from an infinity in-focus condition to a close-object in-focus condition is performed by moving the fourth lens unit along the optical axis.

Abstract: A head-up display in accordance with the present disclosure includes a display device that displays an image toward a vertically downward direction, a first mirror that reflects the image to output reflected light toward a vertically upward direction, and a second mirror that reflects the reflected light from the first mirror to output reflected light toward a vertically upward direction. Also, a vehicle in accordance with the present disclosure includes a head-up display in accordance with the present disclosure, and a windshield that reflects reflected light emitted from the head-up display. The present disclosure makes it possible to provide a thin head-up display.

Abstract: A display apparatus includes: a display device that displays an image; and a projection optical system that projects the image displayed at the display device. The projection optical system includes first and second mirrors in order along an optical path from the display device to a viewer (to guide the image to a viewer's viewpoint area to display a virtual image). The apparatus satisfies conditions of ?x>?y (?x: an incident angle in a longitudinal direction of the image on the first mirror, ?y: an incident angle in a crosswise direction of the image on the first mirror) and 0.2<D1/Lh<0.9 (D1: a distance between an image display surface of the display device and the first mirror (an optical path length at a center of the viewpoint area, Lh: a horizontal width of a virtual image visually recognized by the viewer).

Abstract: A lens system including: a positive most-object-side lens unit; a first most-image-side lens element; and a second most-image-side lens element, wherein the most-object-side lens unit is fixed in focusing, at least one of the first and second most-image-side lens elements has negative optical power, and the conditions: 0.5<DAIR/Y and 1.5<DIM/DOB<4.0 (DAIR: maximum value of air spaces between the lens elements constituting the lens system in an infinity in-focus condition, Y=f×tan ?, f: focal length of the lens system, ?: half view angle of the lens system, DOB: optical axial thickness of the most-object-side lens unit, DIM: optical axial distance from an object side surface of a most-object-side lens element in a lens unit located immediately on the image side relative to the most-object-side lens unit, to an image side surface of the first most-image-side lens element) are satisfied.

Abstract: An inner focus lens system comprising lens units each composed of at least one lens element, wherein a most object side lens unit is provided and is fixed with respect to an image surface in focusing, and the conditions: BF/Y<1.7 and (L×FNo)/f<2.2 (BF: a distance from an image side surface apex of a most image side lens element to the image surface, Y=f ×tan ?, L: an overall length of lens system, FNo: a F-number of lens system,f: a focal length of lens system, ?: a half view angle of lens system) are simultaneously satisfied, or only the condition: (L×FNo)/f<2.0 (L: the overall length of lens system, FNo: the F-number of lens system,f: the focal length of lens system) is satisfied.

Abstract: A zoom lens system, in order from an object side to an image side, comprising: a first lens unit having positive optical power; a second lens unit having negative optical power; a third lens unit having positive optical power; a fourth lens unit having negative optical power; a fifth lens unit; and a sixth lens unit, wherein in zooming from a wide-angle limit to a telephoto limit at a time of image taking, the first lens unit, the second lens unit, the third lens unit, and the fourth lens unit move along an optical axis so that an interval between the third lens unit and the fourth lens unit at the telephoto limit is larger than that at the wide-angle limit, and wherein focusing from an infinity in-focus condition to a close-object in-focus condition is performed by moving the fourth lens unit along the optical axis.

Abstract: A zoom lens system comprising: a positive first lens unit composed of three or more lens elements; a negative second lens unit; a positive third lens unit; a negative fourth lens unit; and a positive fifth lens unit, wherein at least the first, second and third lens units move with respect to an image surface in zooming, a focusing lens unit, which moves with respect to the image surface in focusing and is composed of one lens element, is provided, and the conditions: 3.2<LG3/(fT×tan(?T)) and 0.3<fG1/fT<0.9 (LG3: optical axial thickness of third lens unit, fT: focal length of zoom lens system at telephoto limit, ?T: half view angle at telephoto limit, fG1: focal length of first lens unit) are satisfied.

Abstract: An inner focus lens system comprising lens units each composed of at least one lens element, wherein a most object side lens unit is provided and is fixed with respect to an image surface in focusing, and the conditions: BF/Y<1.7 and (L×FNo)/f<2.2 (BF: a distance from an image side surface apex of a most image side lens element to the image surface, Y=f×tan ?, L: an overall length of lens system, FNo: a F-number of lens system, f: a focal length of lens system, ?: a half view angle of lens system) are simultaneously satisfied, or only the condition: (L×FNo)/f<2.0 (L: the overall length of lens system, FNo: the F-number of lens system, f: the focal length of lens system) is satisfied.