Patent ID: 9300929
Filing Date: 2016-03-29
CPC Classification: G02B,G03B,H04N

Claim Text:
1. An illumination device comprising: a substrate including a fluorescent layer, and capable of rotating around a predetermined rotary shaft, the fluorescent layer having a ring-shape around the rotary shaft; a light source, the light source intermittently emitting an excitation light to excite the fluorescent layer; an emission timing generation device adapted to generate an emission timing signal for controlling an emission timing of the light source, the emission timing signal having a period synchronous with a frame period; a rotational period determination device adapted to control the rotation of the substrate so that the rotation of the substrate is asynchronous with emission of the excitation light, and so that, when the substrate is rotating, a first area of the fluorescent layer is irradiated with the excitation light in one round, and at least a part of the first area is not irradiated with the excitation light in another round; and an electric motor adapted to rotate the substrate, a cumulative light intensity of the excitation light incident on a first area of the florescent layer per unit time being equal to a cumulative light intensity of the excitation light incident on a second area of the florescent layer per unit time, the second area being a different area from the first area along a rotational direction of the substrate, and the cumulative light intensity of the excitation light incident per unit time being equal between all areas of the fluorescent layer, wherein the rotational period determination device determines a period, which is(1+δ) times of a period of the emission timing signal, as a rotational period of the substrate, where δ (0<δ<1) is a duty ratio of a light-emitting period of the light source.