Interactive display device and control method thereof

An interactive display device comprising:

• a pixel sensor unit configured to scan a shape of an external device;
• an identification marker sensor unit configured to sense a signal of an identification marker;
• a display unit configured to display data;
• and
• a controller, configured to:
• detect the external device on the display unit, wherein the external device includes a plurality of identification markers sensed by the identification marker sensor unit,
• scan a shape of the external device,
• sense signals of the identification markers,
• determine coordinate information and contact information of the external device on the display unit based on a result of scanning the shape and sensing the signals, wherein the contact information indicates which side of the external device is in contact with the interactive display device, and
• display data around the external device according to the determined coordinate information and contact information,
• wherein a result of scanning the shape of the external device is an image including a gradation region,
• wherein a tilt angle of the external device is determined according to a brightness ratio of the gradation region, and
• wherein a direction of the external device is determined according to a direction of the gradation region.