A display device of the embodiment includes an image generating unit which emits a light including an image information, and a light guide optical system which generates an image from the light which is emitted from the image generating unit at a position of an exit pupil, in which the light guide optical system is provided with a first mirror (a first deflection unit) which deflects the light which is emitted from the image generating unit, and a second mirror (a second deflection unit) which further deflects the light which is deflected by the first mirror to guide the light to the position of the exit pupil and transmits a portion of external light, and in which an optical axis of the light which propagates from the first mirror toward the second mirror and an optical axis of the exit pupil form an acute angle.

There is provided a lens array and an lens array capable of suitably preventing irregular brightness without reducing resolution. A micro lens array of a screen includes upper-level microlenses and lower-level microlenses which are formed on the incidence surface of the screen, which have the same effective diameter, and which have a structure that generates an optical path length difference Δ in transmission light. By disposing the upper-level microlenses and the lower-level microlenses at an interval based on the effective diameter, the basic periodic structure of a lens period is formed. Further, the upper-level microlenses and the lower-level microlenses form a basic block comprising a combination of the lenses having a structure that generates the optical path length difference. A concave-and-convex period PC based on the basic block is an integer multiple of the lens period.

A head up display cluster arrangement for a motor vehicle includes a dashboard disposed within a passenger compartment of the motor vehicle. The dashboard includes an instrument cluster surface disposed above a steering column of the motor vehicle. An image source is disposed on, or adjacent to, the dashboard. The image source emits an illuminated image. A mirror is positioned to reflect the emitted illuminated image onto the cluster surface.

A head-up display of the present disclosure projects a display image on a transparent reflecting member. The head-up display includes: a display device that displays the display image; and a projection optical system that projects the display image displayed on the display device. On an assumption that light reaching a center of a viewpoint region of the observer and corresponding to a center of the virtual image is reference light, the projection optical system includes a prism element that has an incident surface, a reflection surface, and an emitting surface different from the incident surface sequentially in an optical path from the display device. The emitting surface is inclined to the reference light. An inclination amount θ.sub.2 of the reference light emitted from the emitting surface with respect to the emitting surface lies in a range of 15°<|θ.sub.2|<45° in the optical path from the display device.

An image display device with which it is possible to visually recognize an image while securing the see-through property regardless of eye movements and changes in interpupillary distance, with which it is possible to display a large-size image with high quality, and which is small, has excellent wearability, and has an excellent external appearance.

An image display apparatus includes a light source device including a light source unit; a scanning optical system including an image forming unit on which an intermediate image is formed by light from the light source unit; and a virtual image optical system configured to guide light of the intermediate image by using a reflecting mirror and a curved transmissive reflection member. The scanning optical system includes an optical scanning unit configured to scan the light from the light source unit in a main scanning direction and a sub-scanning direction of the image forming unit. The image forming unit is a transmissive member curved with a convex surface toward the reflecting mirror.

A virtual image display device includes an image light generation device generating image light, a transmissive tilted mirror reflecting the image light from the image light generation device, and a concave transmissive mirror having a concave shape and reflecting, toward the transmissive tilted mirror, the image light reflected by the transmissive tilted mirror to form an exit pupil. The virtual image display device further includes an absorber layer or an absorption film on an external side of a transmissive reflective surface formed in the concave transmissive mirror.

An optical apparatus for a near-eye display includes a microdisplay to emit image light and one or more field lenses positioned to receive the image light from the microdisplay. The one or more field lenses have a combined optical power to form a curved intermediate image. A freeform combiner, having an eyeward side and an external side, is positioned to receive the image light from the one or more field lenses and reflect the image light. A curved intermediate image is formed between the freeform combiner and the one or more field lenses.

To downsize a head-up display apparatus, a recess is provided by cutting a part of the reflection mirror having a quadrilateral shape as a basic shape. A head-up display apparatus includes, in a casing thereof, an image display and an optical path forming member. The optical path forming member includes at least a reflection mirror that reflects the image. The reflection mirror has a quadrilateral shape as a basic shape. The reflection mirror having the quadrilateral shape as the basic shape includes a recess in at least one of four corners. The reflection mirror having the quadrilateral shape as the basic shape is disposed in the casing to be inclined relative to a horizontal direction. The recess is provided in at least one of a top corner and a bottom corner which are diagonally placed in the inclined reflection mirror.

A vehicle head-up display device includes a stepping motor that outputs a rotation to adjust an optical position of a reflecting mirror, a zero detection unit that detects a zero position by the rotation of the stepping motor in a return-to-zero direction, an initial adjustment unit that adjusts the optical position to an initial position based on the zero position by the rotation of the stepping motor in an away-from-zero direction, and a user adjustment unit that, after the adjustment of the initial position, adjusts the optical position to a command position based on the zero position responsive to a command from the vehicle user. The zero detection unit sets a higher rotation speed of the stepping motor than the user adjustment unit, and sets a lower output torque than the user adjustment unit.