Patent ID: 7252392

Claim:
An illumination apparatus which applies light from light sources to a region to be illuminated, comprising: a plurality of light emitting members which are the light sources; an emitted light quantity control unit configured to control emitted light quantities of the plurality of light emitting members; and a light transmissibility changing unit configured to be capable of controlling transmissibility of each light path which transmits output light of the light emitting member to the region to be illuminated; wherein: the emitted light quantity control unit controls the emitted light quantity and the light transmissibility changing unit controls the transmissibility in such a manner that an illuminative light quantity P in the region to be illuminated during intermittent lighting of a predetermined number n of light emitting members which are some of the plurality of light emitting members at a driving current value larger than a rated current in a predetermined period T is larger than an illuminative light quantity P-typ in the region to be illuminated during constant lighting of the predetermined number n of light emitting members at a rated driving current I-typ in the predetermined period T; the emitted light quantity control unit is configured to control a light emission timing, a light emission time, and a driving current value in such a manner that three factors are correlated with one another in a case where the light emitting members are allowed to intermittently emit the light in accordance with the transmissibility obtained by periodically controlling the transmissibility of each light path by the light transmissibility changing unit; and assuming that the number of the light emitting members simultaneously emitting the light is n, the number of each of the n light emitting members simultaneously emitting the light is j, brightness of the n light emitting members at a pulse time supply current I j -pulse is L j (t), a ratio of the light quantity of the light of the n light emitting members guided to the region to be illuminated via the light transmissibility changing unit is K j (t), brightness at a rated current I j -typ in constant lighting of the n light emitting members is L j -typ, a ratio of an optimum light quantity, at which the light transmissibility changing unit does not change with time to maximize the illuminative light quantity P-typ is K j -stop, and a predetermined period is T, the emitted light quantity control unit is configured to control the light emission timing, the light emission time, and the driving current value in the plurality of light emitting members in such a manner as to satisfy the following condition equation: P = ∫ 0 T ⁢ ∑ j = 1 n ⁢ { L j ⁡ ( t ) × K j ⁡ ( t ) } ⁢ ⅆ t > P ⁢ - ⁢ typ = ∑ j = 1 n ⁢ { L j ⁢ - ⁢ typ × K j ⁢ - ⁢ stop } × T ⁢ .