Patent ID: 7425074

Claim:
A display device comprising: an image forming unit forming an image by using an emitted light and an inputted image signal; a projection unit projecting the image formed by the image forming unit onto a screen; and a periodically movable displacement plate displacing the image displayed on the screen between a plurality of different positions on the screen; wherein an optical path difference (D) between lights generated by the displacement plate is given by: D = T cos ⁢ ⁢ θ 2 ⁢ sin ⁡ ( θ 1 - θ 2 ) cos ⁢ ⁢ θ 2 = T x , sin ⁡ ( θ 1 - θ 2 ) = D x , ⁢ θ 2 = sin - 1 ⁡ ( n 1 ⁢ ⁢ sin ⁢ ⁢ θ 1 n 2 ) where, n 1 is a refractive index of air; n 2 is a refractive index of the displacement plate; θ 1 is an incident angle of light; θ 2 is a refraction angle of light; T is a thickness of the displacement plate; and χ is a length of the optical path within the displacement plate.