Projector

A projector, comprising:

• a light engine configured to generate a first polarized beam;
• a polarization changing mechanism which is movable and comprises a first quarter wavelength plate and a second quarter wavelength plate, wherein the first quarter wavelength plate and the second quarter wavelength plate are rotatable relative to each other;
• and
• a polarized beam splitter having a light splitting surface;
• wherein the first polarized beam transforms into a second polarized beam when the first polarized beam passes through the first quarter wavelength plate and the second quarter wavelength plate in order;
• wherein the second polarized beam enters the polarized beam splitter and is guided by the light splitting surface to travel in a first direction or a second direction.

A projector, comprising:

• a light engine configured to generate a first polarized beam;
• a polarization changing mechanism which is movable and comprises a first quarter wavelength plate having a first transmission axis and a second quarter wavelength plate having a second transmission axis;
• and
• a polarized beam splitter having a light splitting surface;
• wherein the first polarized beam transforms into a second polarized beam when the first polarized beam passes through the first quarter wavelength plate and the second quarter wavelength plate in order;
• wherein a first angle between the first transmission axis and a polarization direction of the first polarized beam is 45 degrees;
• wherein the second polarized beam enters the polarized beam splitter and is guided by the light splitting surface to travel in a first direction or a second direction when a second angle between the first transmission axis and the second transmission axis is 0 degrees, 22.5 degrees, 45 degrees or 180 degrees.