Patent ID: 7827422

Claim:
A portable display device, comprising: a first panel for emitting light in a first direction; a second panel for emitting light in a second direction; a substrate disposed between the first panel and the second panel; a first power supply unit for applying a power supply voltage to the first panel; a second power supply unit for applying a power supply voltage to the second panel; a switch control unit for selectively controlling the first power supply unit and the second power supply unit; a first positive power supply voltage unit electrically coupled to the first power supply unit and for applying a positive power supply voltage to the first panel; a second positive power supply voltage unit electrically connected to the second power supply unit for applying a positive power supply voltage to the second panel; a first negative power supply voltage unit electrically coupled to the first power supply unit for applying a negative power supply voltage to the first panel; and a second negative power supply voltage unit electrically connected to the second power supply unit for applying a negative power supply voltage to the second panel; wherein any one of the first panel and the second panel is an organic light emitting diode; and wherein the first negative power supply voltage unit and the second negative power supply voltage unit are electrically coupled to each other.