Stereoscopic image display device

A stereoscopic image display device comprising:

• an image display unit including a plurality of unit pixels arranged in matrix, for forming images on a display surface thereof, each of the unit pixels including a pixel for a left viewing field and a pixel for a right viewing field;
• a gradient-refractive-index liquid-crystal lens arranged at an observer's side of the display surface of the image display unit, the liquid-crystal lens including
• a liquid-crystal cell including two transparent substrates facing each other, a liquid crystal layer put between the transparent substrates, and polarization elements formed on the transparent substrates, respectively,
• a plurality of electrode groups formed on a surface facing the liquid crystal layer of one of the transparent substrates, each of the electrode groups including a plurality of stripe-shaped transparent electrodes corresponding to a column of the unit pixels of the image display unit, and
• a counter transparent electrode formed on the other of the transparent substrates and having a constant potential;
• and
• a liquid-crystal lens drive circuit for driving the liquid-crystal lens, the liquid-crystal lens drive circuit being configured to
• apply voltages to the plurality of transparent electrodes with forming a common voltage pattern for each of the electrode groups so as to make liquid crystal of the liquid crystal layer work as a plurality of lenses forming a predetermined refractive-index profile for each of the electrode groups by driving the liquid crystal by using a voltage difference between the plurality of transparent electrodes and the counter transparent electrode, and
• shift the voltage pattern according to information of a viewpoint position of an observer so as to shift the refractive-index profile of each of the lenses.