US Patent 7377656 Projector

A projector of rear-projection type including a light source that outputs a laser beam and a scanner that scans a screen with the laser beam. When a laser beam with energy exceeds an accessible emission limit due to failure of the light source or the scanner, at least one optical member located in an optical path of the laser beam is arranged so as to be broken or altered in quality and to prevent or discourage the beam with energy exceeding the accessible emission limit from being output from the screen.