Abstract: A screen assembly for projecting an optical image thereon has a screen unit of a type including a screen casing, a winding spindle housed within the screen casing, a screen sheet having one end secured to the winding spindle and the other end situated outside the screen casing, and a screen winder for automatically retracting the screen sheet, once drawn out of the screen casing, into the screen casing, and a screen suspending and tilting mechanism. The screen suspending and tilting mechanism has a suspending column by which the screen casing is supported from an overhead supporting structure, and a tilt angle adjusting mechanism for tilting the screen sheet substantially about the longitudinal axis of the screen casing for the purpose of correcting a linear distortion which may otherwise occur in the projected image if the relative position of the projector and the screen is incorrect.