Patent ID: 8690349

Claim:
A projection type display apparatus comprising: an oblique projection optical system including a group of lenses consisting of a plurality of lenses for enlarging an image displayed on a display screen of a display device and obliquely projecting an enlarged image on a projection screen; a mirror for reflecting an optical path arranged between the first lens and the projection screen, wherein: the group of lenses comprises a first lens arranged at a position optically nearest to the projection screen, the first lens has an effective image area through which a light flux of the image is passed and has such a shape that a portion which does not include the effective image area is truncated, an upper end of a vertical effective image area of the first lens is located above a lower end of a vertical effective image area of the mirror, the mirror has a predetermined angle of elevation with respect to an optical axis, and the mirror is provided with a mirror moving mechanism adaptable to move the mirror along the optical axis.