Illumination apparatus

An illumination apparatus, comprising:

• an OLED (Organic Light Emitting Diode) unit that is constituted by coupling a plurality of singular OLED devices to each other in serial;
• and
• a driving electric power source that drives the OLED unit in a pulse driving mode;
• wherein the driving electric power source comprises:
• a pulse generating section to generate pulses, a duty ratio of which corresponds to brightness command information for designating a brightness of light to be emitted by the OLED unit;
• an OLED driving section to drive the OLED unit to make the OLED unit emit pulsed light corresponding to the pulses generated by the pulse generating section;
• a voltage source to supply a first electric power to the OLED unit, only during a time when each of the pulses is an ON state;
• a voltage source to supply a second electric power to the OLED unit, only during a time when each of the pulses is an OFF state;
• a current source to supply a third electric power to the OLED unit, only during a time when each of the pulses is an ON state;
• a switchover section that conducts a switchover operation between the voltage source and the current source during a time when the duty ratio of the pulses is increasing, in a manner that the voltage source is employed for supplying the first electric power to the OLED unit to make the OLED unit emit the pulsed light when the duty ratio is lower than a second threshold value, being higher than a first threshold value established in advance, while the current source is employed for supplying the third electric power to the OLED unit to make the OLED unit emit the pulsed light when the duty ratio becomes equal to or higher than the second threshold value, and that conducts another switchover operation between the voltage source and the current source during a time when the duty ratio of the pulses is decreasing, in a manner that the current source is employed for supplying the third electric power to the OLED unit to make the OLED unit emit the pulsed light when the duty ratio is equal to or higher than the first threshold value, while the voltage source is employed for supplying the first electric power to the OLED unit to make the OLED unit emit the pulsed light when the duty ratio becomes lower than the first threshold value;
• and
• an OLED illumination disabling section that makes the voltage source supply the second electric power to the OLED unit, only during the time when each of the pulses is the OFF state, to disable the OLED unit to emit light.