BACK PROJECTION DISPLAY DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a back projection display device which is made thin and compact while holding an excellent optical performance. SOLUTION: This device is provided with a projection optical system by which the picture of a panel display surface is obliquely projected on a screen surface 12 and which is axially asymmetric and plane mirror system M1 and M2 to bend an optical path from the projection optical system to the screen surface 12, and the projection optical system has at least one free bent surface reflection surface. A luminous flux from the projection optical system is reflected by the plane reflection surface of the second mirror M2, and reaches the screen surface 12 by crossing the optical path from the projection optical system to the plane reflection surface of the second mirror M2 after being reflected by the plane reflection surface of the first mirror M1 opposed to the screen surface 12.