Display device and method of sensing characteristics of thin film transistors having different types of electrical characteristics

A method of sensing element characteristics of a display device comprising subpixels including a data line, a scan line, a second switching TFT having gate, drain and source nodes, inputting a reference signal through the drain node and outputting the reference signal to the source node, and a first switching TFT having gate, drain and source nodes, the drain node connected to the source node of the second switching TFT, and the source node connected to the data line, the method comprising:

• applying a second scan signal to the second switching TFT to output the reference signal input through the drain node to the source node;
• applying a first scan signal to the first switching TFT to output the reference signal input through the drain node to the source node;
• and
• sensing a voltage of a current transmitted to the data line through the first switching TFT and sensing a threshold voltage of the first switching TFT based on the sensed voltage.

A display device comprising subpixels including a data line, a scan line, and a plurality of thin film transistors (TFTs), comprising:

• a second switching TFT having gate, drain and source nodes, outputting a reference signal input through the drain node to the source node according to a second scan signal input through the gate node;
• a first switching TFT having gate, drain and source nodes, the drain node of the first switching TFT directly connected to the source node of the second switching TFT, and forming a current path such that the reference signal input through the drain node is transmitted to the data line connected to the source node of the first switching TFT according to a first scan signal input through the gate node;
• and
• an IC unit, when a predetermined condition is satisfied, being switched to a diagnostic mode, sensing a voltage of a current transmitted to the data line through the first switching TFT, sensing a threshold voltage of the first switching TFT based on the sensed voltage, and reporting the sensed threshold voltage of the first switching TFT to a server of a customer service center,
• wherein the reference signal, the first scan signal and the second scan signal are generated from the IC unit.

A display device comprising subpixels including a data line, a scan line, and a plurality of thin film transistors (TFTs), comprising:

• a second switching TFT having gate, drain and source nodes, outputting a reference signal input through the drain node to the source node according to a second scan signal input through the gate node;
• a first switching TFT having gate, drain and source nodes, the drain node of the first switching TFT directly connected to the source node of the second switching TFT, and forming a current path such that the reference signal input through the drain node is transmitted to the data line connected to the source node of the first switching TFT according to a first scan signal input through the gate node;
• and
• an IC unit sensing a voltage of a current transmitted to the data line through the first switching TFT, sensing a threshold voltage of the first switching TFT based on the sensed voltage, and reporting the sensed threshold voltage of the first switching TFT to a server of a customer service center when a quality test is performed on the display device at a production site, a diagnostic function of the display device is selected, or the display device is entered a predetermined diagnostic mode,
• wherein the reference signal, the first scan signal and the second scan signal are generated from the IC unit.