US Patent 9335558 Illumination device and display device

An illumination device including a light source section including a laser light source, and allowing a laser light beam emitted from the laser light source to be output intermittently at a predetermined frequency; an optical element through which the laser light beam passes; and a driver section changing a coherency of the laser light beam by driving the optical element at a predetermined drive frequency. Expressions (1) |2×f2−n1×f1|≧20 or (2) |2×f2−n2×f1|≦3, (3) f2≧20 or (4) f2≦3, and (5) |f2−n1×f1|≧20 or (6) |f2−n3×f1|≦3 are satisfied, where f1 denotes the predetermined frequency in Hz, f2 denotes a variation frequency of luminance in illumination light output from the optical element in Hz, the variation frequency being generated by the driving of the optical element, n1 denotes an arbitrary integer of 0 to 10 both inclusive, and n2 and n3 denote respective predetermined integers of 0 to 10 both inclusive.