Display device and electronic device

A display device comprising:

• a first light emitting element;
• a monitoring second light emitting element;
• a transistor connected in series to the monitoring second light emitting element;
• a constant current source for supplying a constant current to the monitoring second light emitting element;
• and
• a circuit for outputting a potential corresponding to a potential which is inputted to said circuit,
• wherein a first electrode of the first light emitting element is electrically connected to an output terminal of the circuit;
• wherein a first electrode of the monitoring second light emitting element, a gate electrode of the transistor, and one of a source electrode and a drain electrode of the transistor are connected to an input terminal of the circuit;
• and
• wherein the other of the source electrode and the drain electrode of the transistor is connected to an AC power supply.

A display device comprising:

• a first light emitting element;
• a monitoring second light emitting element;
• a constant current source for supplying a constant current to the monitoring second light emitting element;
• a circuit for outputting a potential corresponding to a potential which is inputted to said circuit;
• a capacitor connected to an input terminal of the circuit;
• a first switch provided between a first electrode of the first light emitting element and an output terminal of the circuit;
• a second switch provided between the first electrode of the first light emitting element and an AC power supply;
• a third switch provided between a first electrode of the monitoring second light emitting element and the input terminal of the circuit;
• and
• a fourth switch provided between the first electrode of the monitoring second light emitting element and the AC power supply.

A display device comprising:

• a first light emitting element;
• a monitoring second light emitting element;
• a transistor connected in series to the monitoring second light emitting element;
• and
• a circuit for outputting a potential corresponding to a potential which is inputted to said circuit;
• wherein a first electrode of the first light emitting element is electrically connected to an output terminal of the circuit;
• wherein a first electrode of the monitoring second light emitting element and one of a source electrode and a drain electrode of the transistor are connected to an input terminal of the circuit;
• wherein a gate electrode of the transistor is connected to a first power supply;
• and
• wherein the other of the source electrode and the drain electrode of the transistor is connected to a second power supply.

A display device comprising:

• a first light emitting element;
• a monitoring second light emitting element;
• a constant current source for supplying a constant current to the monitoring second light emitting element;
• a circuit for outputting a potential corresponding to a potential which is inputted to said circuit;
• and
• a resistor provided between a first electrode of the monitoring second light emitting element and an input terminal of the circuit;
• wherein a first electrode of the first light emitting element is electrically connected to an output terminal of the circuit.

A display device comprising:

• a first light emitting element;
• a switching transistor;
• a monitoring second light emitting element;
• a forward bias transistor connected in series to the monitoring second light emitting element;
• a constant current source for supplying a constant current to the monitoring second light emitting element;
• and
• a circuit for outputting a potential corresponding to a potential which is inputted to said circuit;
• wherein a first electrode of the first light emitting element is electrically connected to an output terminal of the circuit;
• wherein a first electrode of the monitoring second light emitting element is connected to an input terminal of the circuit;
• wherein a gate electrode of the switching transistor and a gate electrode of the forward bias transistor are connected to a gate line;
• and
• wherein one of a source electrode and a drain electrode of the forward bias transistor is connected to the input terminal of the circuit and the other of a source electrode and a drain electrode of the forward bias transistor is connected to a forward bias power supply.