Abstract: A screen cover opening device for a television receiver is provided with a screen cover openably closing left and right side portions or upper and lower side portions of a screen adapted for electively displaying plural different aspect ratio images. Two vertically extending rolls 5a, 5b are arranged at outwardly shifted positions from left and right lateral sideswrapped around of the screen 2 and an endless cover sheet 3 is wrapped around these rolls. Two windows 4a, 4b are formed at longitudinally spaced apart positions of the cover sheet 3. The rolls are rotated to run the cover sheet to change overlap of the two windows to change the transverse width W that may be viewed through overlapped portions of the two windows.

Abstract: A display device of projection type capable of projecting an image with well defined image frame is disclosed. The device comprises 3 spatial light modulators on which color image information is written in 3 primary colors respectively and is read out as a combined optical color image in a form of light beam, the light beam is then projected out of the display device through lens groups for forming a projected image on a screen, the device further comprises a mask disposed in a proximity of an imaginary image formation plane arranged to locate in a vicinity of one of the lens groups, the light beam is caused to form an optical image on the imaginary image formation plane. The mask has a variable light shielding configuration controlled either electronically or electro-mechanically for cutting off unnecessary light portions of the light beam carrying the optical image so that an image of high contrast and well defined clear fringe is projected on the screen.