A projection optical system (10) projects from a first image plane (5) on a reducing side to a second image plane (6) on an enlargement side. The projection optical system (10) includes a first optical system (11) that includes a plurality of lenses and forms a first intermediate image (51) formed inside the first optical system (11) by light incident from the reducing side into a second intermediate image (52) on the enlargement side of the first optical system (11); a second optical system (12) that includes a first reflective surface (M1) with positive refractive power which is positioned further to the enlargement side than the second intermediate image (52); and a glass block (30) that is disposed between the first optical system (11) and the first reflective surface (M1), the glass block (30) passing light rays from the first optical system (11) to the second intermediate image (52).

A processing device generates a marker image to use as a reference for correcting a shape of a projection image projected on a projection surface from a projector, takes a taken image of the projection surface using the imaging device from an imaging position different from an observation position from which the projection surface is observed, generates a parameter for reducing a distortion of the projection image based on the marker image included in the taken image, displays an area image representing a range wherein projection can be performed on the projection surface on the display device, disposes a video content at an indicating position in the area image with an input to the input device, generates an original image including the video content, and corrects the original image thereby generating an input image for input to a projector configured to project the projection image.

A first holding member holds a first optical system and a first mirror, and has a first junction surface. A second holding member holds a second optical system and a second mirror, and has a second junction surface. A junction portion is configured such that, in a state where the first junction surface and the second junction surface are aligned with each other, the second holding member is capable of being shifted in a direction of both the junction surfaces and rotated around an optical axis, and makes it possible to perform optical axis alignment. An emission-side optical axis of the first optical system and an incidence-side optical axis of the second optical system are aligned with each other, and thus a U-shaped optical path is formed by the first and second optical systems.

A lens shift mechanism of one embodiment of the present disclosure includes: a projection lens; a cylindrical housing that holds the projection lens; and an operating unit that moves the cylindrical housing in one axial direction perpendicular to an optical axis of the projection lens. The operating unit includes a pair of a main shaft and a countershaft extending in the one axial direction and disposed to be opposed to each other across the cylindrical housing, and a pair of elastic bodies provided respectively for the main shaft and the countershaft. The pair of elastic bodies are parallel to the one axial direction, and have biasing directions opposite to each other.

The 1-2nd lens group is divided into three lens groups which move when focusing is performed during the magnification change. Even in a case in which the second optical group is formed of one mirror, it is possible for a primary image to contain appropriate aberration and to hereby reduce aberration of an image which is finally projected onto a screen through the second optical group.

A projector includes a manipulation detecting unit that performs a manipulation detecting process on the basis of captured image data of an imaging unit, and a correction control unit that performs a distortion correcting process on the basis of the captured image data. An imaging control unit sets an image-capturing resolution of the imaging unit to resolutions different from each other between a case where the manipulation detecting unit performs the manipulation detection process and a case where the correction control unit performs the distortion correcting process.

A projection lens, which is mounted on a housing of a projection device including an electro-optical element, includes a first holding part that holds a first optical system disposed along a first optical axis along which light emitted from the housing passes, a first reflective part that bends light parallel to the first optical axis to form light parallel to a second optical axis, a second reflective part that bends the light parallel to the second optical axis to form light parallel to a third optical axis, and a second holding part holds the first reflective part and the second reflective part. A distance along the first optical axis between a first lens, which is disposed to be closest to a reduction side in the first optical system, and the first reflective part is longer than a distance along the second optical axis between the first reflective part and the second reflective part. The first optical system includes a second lens that is disposed to be closest to an enlargement side to form an intermediate image of an optical image of the electro-optical element.

An optical compensation element adjusting mechanism capable of adjusting an inclination of an optical compensation element with high accuracy and a projector. The mechanism includes an optical compensation element which optically compensates a liquid crystal panel and an adjusting frame which adjusts an angle of the element to the liquid crystal panel. The adjusting frame includes an approximately rectangular holding portion which holds the optical compensation element, a pair of fixing portions which respectively extends from positions, which become a diagonal, of the holding portion in a direction intersecting with the holding portion and which is respectively fixed to a first holding member to which the adjusting frame is attached, and an adjusting portion which is disposed at a position away from the pair of fixing portions and which inclines the optical compensation element by inclining the holding portion around a virtual line connecting the pair of fixing portions.

A keyboard device includes a keyboard body including a plurality of keys. A projector is disposed in the keyboard body for receiving and transforming an image signal into a projection frame, and projecting the projection frame on a projection plane. A vibration sensor is disposed in the keyboard body, and generates a vibration signal in response to a vibration of the keyboard body. A microprocessor is in communication with the vibration sensor and the projector, dynamically adjusts the image signal according to the vibration signal, and outputs the adjusted image signal to the projector to generate the projection frame corresponding to the adjusted image signal. The shaking problem of the projection frame can thus be ameliorated.

A cinema theater includes a seating area, a curved screen in front of the seating area and at least one projector. In one aspect, the seating area is preferably a stadium seating area and the at least one projector is positioned behind and above the stadium seating area. In another aspect, the curved screen has a center point and the at least one projector is mounted at an angle of incidence to the center point of the screen of between ±5° horizontal and ±5° vertical. In yet another aspect, the seating area that has an upper seating area and a lower seating area and the at least one projector is positioned at the front of the upper seating area.