An electronic device including a display panel having an optical plate attached thereon is disclosed. The optical plate includes a parallax separation sheet to allow a user to see a 3D image displayed on the display panel, and a touch-sensing layer to allow a user to select stored items such as pictures in the electronic device or to enter information into the electronic device. A method for assembly the electronic device is also disclosed. The method uses three cameras and three monitors to check the alignment between the optical plate and display panel. In order to achieve a correct alignment, rotating device and shifting device can be used to adjust the position of the display panel relative to the optical plate.