Image display device

1. An image display device comprising:

a light emitting unit that emits light by current injection;

a driving unit that includes a first terminal and a second terminal, and controls current flowing through the light emitting unit based on a potential difference applied between the first terminal and the second terminal, the potential difference being higher than a predetermined drive threshold;

a threshold potential detecting unit that detects the potential difference;

a luminance potential supplying unit that changes an absolute value of the potential difference to a value lower than the drive threshold by a luminance potential corresponding to a luminance of the light emitting unit; and

a sweep potential supplying unit that controls the driving unit by supplying a sweep potential to the first terminal after the absolute value of the potential difference is changed by the luminance potential supplying unit, the sweep potential being swept in a range between a value lower than the luminance potential and a value higher than the luminance potential,

wherein the driving unit includes a thin film transistor that has a gate connected to the first terminal, a source connected to the second terminal, and a drain,

the threshold potential detecting unit includes a first switching unit that detects the potential difference by shorting between the gate and the drain,

the luminance potential supplying unit includes an electrostatic capacity that has a first electrode connected to the gate and a second electrode opposite to the first electrode, and a potential supply source that supplies a potential to the second electrode, and

a potential of the second electrode is changed from a reference potential by the luminance potential when the first switching unit shorts between the gate and the drain, and the potential of the second electrode is changed to the reference potential again after the gate and the drain are shorted, thereby a potential difference between the gate and the source drops by the luminance potential.

2. The image display device according to claim 1 , wherein the sweep potential supplying unit is integrated with the luminance potential supplying unit, and

the potential supply source supplies the sweep potential to the gate through the electrostatic capacity while a circuit between the gate and the drain is opened by the first switching unit.

3. The image display device according to claim 1 , further comprising:

a current source that supplies the current to the light emitting unit;

a second switching element that opens a circuit between the current source and the light emitting unit when the threshold potential detecting unit and the luminance potential supplying unit are operated, and electrically connects between the current source and the light emitting unit when the sweep potential supplying unit is operated; and

a third switching unit that controls a conduction between the potential supply source and the second electrode,

wherein the first switching unit, the second switching unit, and the third switching unit include a thin film transistor whose conductive type is the same as conductive type of the thin film transistor of the driving unit.

4. The image display device according to claim 1 , wherein the light emitting unit is an organic light emitting diode.