Stereoscopic display for switching between 2D/3D images

A stereoscopic display for switching between a two-dimensional (2D) image and a three-dimensional (3D) image, the stereoscopic display comprising:

• a display device which displays an image;
• and
• a parallax barrier unit which substantially transmits incident light in a 2D mode, and forms barriers to substantially separate an image for a left eye from an image for a right eye in a 3D mode,
• wherein the parallax barrier unit comprises:
• a first polarization plate which transmits light with a first polarization direction;
• a first polarization grating screen including a first birefringence element that changes the polarization direction of light transmitted through the first polarization plate into a first direction and a second birefringence element that changes the polarization direction of light transmitted through the first polarization plate into a second direction substantially opposite to the first direction, wherein the first birefringence element and the second birefringence element alternate with each other in a grating pattern;
• a second polarization grating screen which faces the first polarization grating screen and includes a third birefringence element that changes the polarization direction of light transmitted through the first polarization grating screen into the first direction and a fourth birefringence element changing the polarization direction of light transmitted through the first polarization grating screen into the second direction substantially opposite to the first direction, wherein the third birefringence element and the fourth birefringence element alternate with each other in said grating pattern;
• and
• a second polarization plate which faces the second polarization grating screen and transmits only light with a second polarization direction among lights transmitted through the second polarization grating screen.