A display device includes a display panel, a polarization film, and a wave plate. Below the wave plate and the polarization film there is provided a plurality of optical sensors disposed within the display panel. The display panel includes first and second substrates facing each other and a plurality of pixels configured to display an image. The optical sensors are configured to sense light in one or more predetermined light bands. The wave plate is configured to rotate polarization of first light that has passed upwardly through the polarization film such that the combination of upward and downward (reflected) passage of the light is rotated by about 90 degrees. The so-rotated light is blocked from passing down through the polarization film; advantageously, the so-rotated light is prevented from interfering with the optical sensors.