Patent ID: 7570233

Claim:
A display device comprising: an external correction circuit including a power source and a signal generator; and a panel being connected to the external correction circuit through a flexible printed wiring, the panel including: a signal line driver circuit, a scan line driver circuit, a pixel portion including a first thin film transistor, a second thin film transistor and a light-emitting element, a monitoring element portion including a monitoring element and a monitoring line, a D/A converter, and a constant current source circuit, which are formed over a substrate, wherein the signal generator is configured to send a video signal to the signal line driver circuit and the D/A converter through a video signal line, wherein the D/A converter is configured to convert the video signal into an analog signal and to send the analog signal to the constant current source circuit, wherein the constant current source circuit is configured to supply a constant current to the monitoring element through the monitoring line, and a current value of the constant current is controlled based on a potential of the analog signal, wherein a potential of the monitoring line, which corresponds to a potential difference of the monitoring element, is inputted into the external correction circuit, wherein the signal line driver circuit is configured to send the video signal to one of a source and a drain of the first thin film transistor, wherein the other of the source and the drain of the first thin film transistor is electrically connected to a gate of the second thin film transistor, and a gate of the first thin film transistor is electrically connected to the scan line driver circuit, wherein one of a source and a drain of the second thin film transistor is electrically connected to the light-emitting element, and wherein the external correction circuit is configured to send the potential of the monitoring line to the other of the source and the drain of the second thin film transistor.