Method for controlling external device and remote controller thereof

A display device comprising:

• a remote controller,
• a display module;
• a first interface to transmit and receive a signal to and from the remote controller;
• a second interface to transmit and receive a signal to and from at least one external apparatus;
• and
• a processing unit to output processed data to the display module to display a video,
• wherein when the first interface wirelessly receives a remote control signal regarding a first external apparatus from the remote controller, the second interface wirelessly transmits the remote control signal to the first external apparatus, and
• wherein the remote controller includes:
• a receiving unit to wirelessly receive information regarding the at least one external apparatus;
• a touch panel to display a plurality of keys;
• a control unit to control the touch panel according to a first display state or a second display state, the first display state for controlling the touch panel to display a first group of keys to control the first external apparatus, and the second display state for controlling the touch panel to display a second group of keys to control a second external apparatus, wherein the first group of keys is different from the second group of keys;
• and
• a transmitting unit to transmit the remote control signal.