Keypad apparatus, mobile device having the same and keypad control method

A keypad device, comprising:

• a touch panel;
• an Organic Light-Emitting Diode (OLED) panel placed under the touch panel, patterned with keypad information, and displaying keypad information corresponding to a light emitting pixel;
• and
• a control unit electrically connected to the touch panel and the OLED panel, and configured to detect an electric signal related to a touch point of the touch panel and cause the pixel of the TOLED panel corresponding to the touch point to emit light.

A method of controlling a keypad device, comprising:

• a control unit detecting an electric signal related to a touch point of a touch panel;
• if the electric signal generated in the touch panel is detected, causing a corresponding pixel to emit light by applying driving voltage to the corresponding pixel of the TOLED panel corresponding to the touch point;
• and
• a reflective sheet patterned with keypad information reflecting keypad information corresponding to a light emitting pixel of the TOLED panel, thereby displaying this keypad information.

A method of controlling a keypad device, comprising:

• a control unit detecting an electric signal related to a touch point of a touch panel;
• if the electric signal generated in the touch panel is detected, causing a corresponding pixel to emit light by applying driving voltage to the corresponding pixel of an OLED panel corresponding to the touch point;
• and
• the OLED panel patterned with keypad information displaying keypad information corresponding to a light emitting pixel.