Patent ID: 7880948

Claim:
A scanning projection device comprising: a light source unit; a deflection member deflecting a beam emitted from the light source unit in a first scanning direction and a second scanning direction which are perpendicular to each other; and a projection optical system guiding the beam deflected by the deflection member onto a scan surface, wherein the scanning projection device two-dimensionally scans an image area on the scan surface with the beam, the first scanning direction is identical with a short-side direction of the image area on the scan surface, and the scanning projection device satisfies the following conditional expressions (1) and (2): 5<θin<60 (1), 1.0 <A /( B×C )<2.5 (2), where A={Sh/Sv }×tan(2 θv ), B= 2 tan(θ h )×cos 2 (θin), C= 1−tan(θin)×tan(2 θv ), θin is an incident angle of a ray entering the scan surface at a minimum angle among rays entering the scan surface within a cross section which includes a principal ray at a center of the image area and is parallel with the short-side direction of the image area, Sh is a length of the image area on the scan surface in a long-side direction, Sv is a length of the image area in the short-side direction, θh is a maximum optical-scan angle in the long-side direction of the image area, and θv is a maximum optical-scan angle in the short-side direction of the image area, and wherein the principal ray at the center of the image area means a ray which is emitted from the light source unit, then passes a center of a diaphragm, and enters the center of the image area on the scan surface.