Patent ID: 9523842
Filing Date: 2016-12-20
CPC Classification: G02B,G03B,H04N

Claim Text:
1. A projection device configured to magnify and project, on a screen, an image displayed at an image display element, the projection device comprising: a dioptric system including at least one positive lens and at least one negative lens; and a reflection optical system having at least one reflection optical element, wherein the at least one positive lens and the at least one negative lens satisfy conditional expressions (1)-(3): dnT denotes a temperature coefficient of a relative refractive index at a D line in a range of 40 to 60 degrees, νd denotes an Abbe number, BF denotes a distance from an intersection between a surface including the image display element and the optical axis, to a vertex of an image display element side surface of a lens closest to the image display element, Y denotes a maximum value of a distance between the optical axis and an end portion of an image forming unit, and the optical axis is an axis shared by a plurality of axisymmetric lenses of the dioptric system.