Touch display device

A touch display device, comprising:

• a display panel, having a light incident plane and a light exit plane, wherein the light exit plane has a first side, a second side adjacent to the first side, a third side opposite to the first side, and a fourth side opposite to the second side;
• a light guide plate, disposed at the light incident plane, wherein the light guide plate has a first side, a second side, a third side opposite to the first side, and a fourth side opposite to the second side, the first side, the second side, the third side, and the fourth side of the light guide plate correspond to the first side, the second side, the third side, and the fourth side of the light exit plane of the display panel respectively, so that the first side, the second side, the third side, and the fourth side of the light guide plate are located on the same sides as the first side, the second side, the third side, and the fourth side of the light exit plane of the display panel respectively, and the light guide plate further comprises a plurality of microstructures disposed on a bottom surface of the light guide plate;
• at least one invisible light emitting device, disposed on at least one side of the light guide plate to emit an invisible light toward the light guide plate;
• and
• a first light path converting device, disposed on the light exit plane and arranged along the first side and the second side of the light exit plane, wherein the invisible light emitted from the invisible light emitting device travels along the first side and the second side of the light guide plate, and the invisible light is guided toward the light incident plane by the microstructures, and penetrates through the display panel so as to reach the first light path converting device.