Abstract: A projection type image display apparatus (1) comprises a focus correction system (30). The system includes a temperature detection mechanism (16) for measuring temperature in the vicinity of a projection lens group (13), a correction amount calculation unit (18) for calculating a correction amount for correcting the focus shift caused by a temperature change, and a driving signal generation unit (19) for generating, based on the correction amount, a driving signal for driving a focus adjustment mechanism (15). If the user performs a focus adjustment using a focus operation input unit (23), a focus operation determination unit (21) determines that a focus adjustment has occurred independently of the focus correction system and changes a correction condition stored in a memory (20).

Abstract: A projection type image display apparatus (1) comprises a focus correction system (30). The system includes a temperature detection mechanism (16) for measuring temperature in the vicinity of a projection lens group (13), a correction amount calculation unit (18) for calculating a correction amount for correcting the focus shift caused by a temperature change, and a driving signal generation unit (19) for generating, based on the correction amount, a driving signal for driving a focus adjustment mechanism (15). If the user performs a focus adjustment using a focus operation input unit (23), a focus operation determination unit (21) determines that a focus adjustment has occurred independently of the focus correction system and changes a correction condition stored in a memory (20).

Abstract: A projection type image display apparatus (1) comprises a focus correction system (30). The system includes a temperature detection mechanism (16) for measuring temperature in the vicinity of a projection lens group (13), a correction amount calculation unit (18) for calculating a correction amount for correcting the focus shift caused by a temperature change, and a driving signal generation unit (19) for generating, based on the correction amount, a driving signal for driving a focus adjustment mechanism (15). If the user performs a focus adjustment using a focus operation input unit (23), a focus operation determination unit (21) determines that a focus adjustment has occurred independently of the focus correction system and changes a correction condition stored in a memory (20).

Abstract: A variable-focal-length lens system for projection which achieves focusing by movement of the entire system has a second to a fourth lens group as focal-length-varying lens groups and a first lens group as a distance-compensation lens group. The second to fourth lens groups individually move in the optical axis direction to vary the group-to-group distances so as to vary the focal length of the entire system. During focusing, the first lens group moves in the optical axis direction such that, as the projection distance varies from a remote distance to a close distance, curvature of field varies to the under side.

Abstract: A variable-focal-length lens system for projection which achieves focusing by movement of the entire system has a second to a fourth lens group as focal-length-varying lens groups and a first lens group as a distance-compensation lens group. The second to fourth lens groups individually move in the optical axis direction to vary the group-to-group distances so as to vary the focal length of the entire system. During focusing, the first lens group moves in the optical axis direction such that, as the projection distance varies from a remote distance to a close distance, curvature of field varies to the under side.

Abstract: A projection type image display apparatus (1) comprises a focus correction system (30). The system includes a temperature detection mechanism (16) for measuring temperature in the vicinity of a projection lens group (13), a correction amount calculation unit (18) for calculating a correction amount for correcting the focus shift caused by a temperature change, and a driving signal generation unit (19) for generating, based on the correction amount, a driving signal for driving a focus adjustment mechanism (15). If the user performs a focus adjustment using a focus operation input unit (23), a focus operation determination unit (21) determines that a focus adjustment has occurred independently of the focus correction system and changes a correction condition stored in a memory (20).

Abstract: A projection lens system 1A enlarges and projects onto a screen 8, via a plurality of lenses G1 to G16, image light emitted from, a light source 4 and modulated by DMDs 3r to 3b. A movable lens barrel 25 holds the lens G16, having positive power, which is positioned closest to the DMDs 3r to 3b. An outer tube 24 holds the movable lens barrel 25 to enable movement in the optical axis direction. Through thermal deformation at the time of an increase in temperature, the bimetal member 27 moves the movable lens barrel 25 in the optical axis direction so as to recede from the image formation devices which are the DMDs 3r to 3b.

Abstract: A projection optical system unit has a lower pedestal. The lower pedestal has first and second tubular portions opened to each other. An image formation device holding plate for a DMD is mounted on the first tubular portion at a side where one opening is formed. A mirror holder for a convex mirror is fixed on the second tubular portion at a side where the other opening is formed. A linear heat expansion coefficient in a specific direction of the lower pedestal component is set between 0.8×10?5 (1/K) and 3.0×10?5 (1/K).

Abstract: A projection lens system 1A enlarges and projects onto a screen 8, via a plurality of lenses G1 to G16, image light emitted from, a light source 4 and modulated by DMDs 3r to 3b. A movable lens barrel 25 holds the lens G16, having positive power, which is positioned closest to the DMDs 3r to 3b. An outer tube 24 holds the movable lens barrel 25 to enable movement in the optical axis direction. Through thermal deformation at the time of an increase in temperature, the bimetal member 27 moves the movable lens barrel 25 in the optical axis direction so as to recede from the image formation devices which are the DMDs 3r to 3b.

Abstract: The present invention provides an injection mold for forming free-form surface optical element that is possible to produce with high accuracy at low cost a free-form surface optical element that has a stable relation between the free-form surface and the mounting reference surface and is easy to adjust when mounting. The mold comprises a fixed mold and a movable mold for forming a free-form surface (effective area 21) and a rear surface opposite to the free-form surface. The fixed mold and the movable mold are divided by a parting line PL along the peripheral end surface of the free-form surface optical element 14. A mold surface for molding the free-form surface (effective area 21) and a mold surface for molding axial-direction mounting reference surfaces 28a-28c for mounting the free-form surface optical element in a direction substantially perpendicular to the free-form surface are positioned in the mold on the same side with respect to the parting line PL.

Abstract: A projection optical system unit has a lower pedestal. The lower pedestal has first and second tubular portions opened to each other. An image formation device holding plate for a DMD is mounted on the first tubular portion at a side where one opening is formed. A mirror holder for a convex mirror is fixed on the second tubular portion at a side where the other opening is formed. A linear heat expansion coefficient in a specific direction of the lower pedestal component is set between 0.8×10?5 (1/K) and 3.0×10?5 (1/K).

Abstract: A projection type image display apparatus has: an illumination optical system generating illumination light; a projection optical system projecting an image light onto a screen; a digital micromirror device (DMD) modulating the illumination light so as to form the image light; and a reflection mirror arranged in a position opposite to an optical path of the illumination light entering the DMD. The reflection mirror reflects an off-light reflected by the DMD in an “OFF” state in a direction separated from a projection light reflected by the DMD in an “ON” state.