Display device with compensation for variations in pixel transistors mobility
In order to efficiently execute threshold value compensation for a driving transistor, a coupling capacitor has one end connected to a data line. Another end of the coupling capacitor is connected to a selection transistor and one end of a reset transistor. A control terminal of a driving transistor is connected to the other end of the selection transistor, and an organic EL element is connected to this driving transistor via a light emission control transistor. A data voltage, corresponding to a gradation signal supplied to the data line, is written to a storage capacitor via the coupling capacitor, and with the selection transistor and the light emission control transistor in an off state and the reset transistor turned on, a compensation voltage corresponding to a degree of mobility of the driving transistor is written to the coupling capacitor.
1. A display device having power supply, including:
pixels arranged in a matrix from, each pixel comprising:
a coupling in one end connected to a data line;
a selection transistor, having one end connected to the coupling capacitor, and which is switchable between ON and OFF states by a selection line connected to a control terminal of the selection transistor;
a driving transistor, having a control terminal connected to the other end of the switching transistor, and one end connected to the power supply;
a light emission control transistor, having one end connected to another end of the driving transistor, and being turned ON and OFF by a light emission control line;
a current driven type light emitting element connected to another end of the light emission control transistor;
a storage capacitor which connects a control terminal of the driving transistor and the one end of the driving transistor that is connected to the power supply side; and
a reset transistor that connects (i) the one end of the light emission control transistor that is connected to the another end of the driving transistor to (ii) the one end of the selection transistor that is connected to the coupling capacitor, and that is turned ON and OFF by a reset line; and
a driver for controlling potential of each line;
wherein,
following (a) the driver writing a data voltage, corresponding to a gradation signal supplied to the data line, to the storage capacitor via the coupling capacitor, and
with (b) the selection transistor and the light emission control transistor in an off state and the reset transistor turned on,
thereby (c) a compensation voltage according to mobility of the driving transistor is developed on the coupling capacitor; and
wherein further,
with (d) the compensation voltage developed on the coupling capacitor in a state where the same gradation signal is supplied to all pixels,
the driver then (e) turns off the selection transistor, and turns on both the light emission control transistor and the reset transistor,
causing (f) a second voltage to be developed on the coupling capacitor that corresponds to a voltage increase across the light emitting element
following which the driver (g) performs equalization processing by causing current to flow in the driving transistor based on the second voltage.
2. The display device of claim 1 , wherein
the current driven type light emitting elements are organic EL elements.
3. The display device of claim 1 , wherein
the driver is capable of varying the time that the reset transistor is turned on with the selection transistor and the light emission control transistors in an off state.
4. The display device of claim 3 , wherein
the current driven type light emitting elements are organic EL elements.
5. The display device of claim 1 , wherein
the driver turns the light emission control transistor on in a state where the selection transistor and the reset transistor are turned off, and after that turns the reset transistor on with the selection transistor and the light emission control transistor turned off.
6. The display device of claim 5 , wherein
the current driven type light emitting elements are organic EL elements.
7. The display device of claim 5 , wherein
the driver is capable of varying the time that the reset transistor is turned on with the selection transistor and the light emission control transistors in an off state.
8. The display device of claim 7 , wherein
the current driven type light emitting elements are organic EL elements.