Stereoscopic display devices that can be viewed with the naked eye fall roughly into the categories of parallax barrier systems and lenticular lens systems. These stereoscopic display devices divide light using a barrier or a lens and project different images into the left eye and the right eye to provide a three-dimensional appearance to a viewer. Two-view parallax barrier systems and lenticular lens systems are the mainstream autostereoscopic display devices available in the market in recent years.
Such two-view stereoscopic display devices provide good stereoscopic display in set areas. However, when a viewer moves the head, a phenomenon called crosstalk, double vision caused by a mixing of an image targeting the right eye and an image targeting the left eye, and so-called pseudo-stereoscopy, in which an image targeting the right eye is projected into the left eye, occur in some regions. For this reason, the viewer can view stereoscopic images only from a limited region. To solve this problem, technologies such as a multi-view technology and a tracking technology, which detects the position of the viewer and displays an image according to that position, have been proposed. However, there is no stereoscopic display device that is capable of providing stereoscopic images from a broad range of angles while maintaining two-view stereoscopic display.
Meanwhile, a liquid crystal lens system that combines the features of both the parallax barrier system and the lenticular lens system has been proposed. This system is capable of switching between a 2D display and a 3D display while maintaining the same level of luminance in the 3D display as in the 2D display. However, with this system, too, stereoscopic display is viewable only from a limited region.
A stereoscopic image display device described in Japanese Patent Application Laid-Open Publication No. 2012-98394 is equipped with a display unit and a liquid crystal lens array element (liquid crystal lens). The liquid crystal lens array element has a first electrode, a plurality of second electrodes, and a liquid crystal layer. The plurality of second electrodes are disposed to face the first electrode, and driving voltages in waveform with phase differences are applied. The liquid crystal layer is interposed between the first electrode and the plurality of second electrodes. A lens effect is produced by the potential differences between the driving voltage applied to the first electrode and the driving voltages applied to the plurality of second electrodes.