Projector and control method

A projector comprising:

• a light-emitting element that outputs light of a first wavelength band which is in a first polarization state;
• a retardation plate that converts a portion of the light output from the light-emitting element into a second polarization state in accordance with a rotation angle of the retardation plate;
• a polarization separation element that separates the light from the retardation plate into a first flux of light in the first polarization state and a second flux of light in a second polarization state;
• a phosphor, excited by the first flux of light, which outputs a third flux of light of a second wavelength band different from the first wavelength band;
• an optical modulator that modulates the light in accordance with a video signal;
• a light-emitting element control unit that controls brightness of the light-emitting element in accordance with brightness information;
• and
• a retardation plate control unit that controls a rotation angle of the retardation plate in accordance with the brightness information.