Patent ID: 7988300

Claim:
An illumination device, comprising: a light source; an optical element for converting light from the light source into parallel light in at least one direction; and a fly-eye lens for allowing incidence of the parallel light from the optical element to guide uniform light to an area for illumination, wherein assuming that a certain number of lens cells in the fly-eye lens in a column direction or a row direction are defined as a lens cell unit, one of the lens cell units is relatively displaced with respect to the other one of the lens cell units in the column direction or the row direction, and the number of steps for displacement among the lens cell units in the fly-eye lens is set to 2 or more, assuming that the number of steps for displacement is “s”, and a size of one lens cell in the displacing direction of the lens cell unit is “P”, a displacement distance “d” of the lens cell unit per step is defined in accordance with the following equation: d=P /( s+ 1).