Patent ID: 8829472

Claim:
An image display device, comprising: an excitation light source; a fluorescent screen that includes a plurality of phosphor regions which are repeatedly formed in an in-plane direction and a retro-reflection region that reflects a part of light that enters the retro-reflection region in a direction opposite to a direction of the light; a scanning unit that scans a surface of said fluorescent screen on which said phosphor regions and said retro-reflection region are formed with excitation light emitted from said excitation light source; a photo detection unit that outputs a signal value that varies on the basis of a quantity of light that enters said photo detection unit; a reflection unit that reflects retro-reflection light of the excitation light directed from said retro-reflection region to said photo detection unit; and a control unit that causes said scanning unit to scan said fluorescent screen, detects boundaries between said phosphor regions and said retro-reflection region on said fluorescent screen based on the output signalof said photo detection unit, and controls a light emission timing of said excitation light source based on the detected boundaries, wherein said reflection unit surrounds or sandwiches a region through which said excitation light passes when said reflection unit is viewed from said fluorescent screen side along an optical path of said excitation light.