Image display apparatus including a non-emission period lowering the gate and source voltage of the drive transistor
View Patent ↗An image display device and method of driving an image display device with alternative repeating of an emission period during which the light emitting element is made to emit light and a non-emission period during which light emission of the light emitting element is stopped. The terminal voltage of a storage capacitor is set to the voltage of a signal line, whereby light emission luminance of the light emitting element in a next emission period is set.
1. An image display device comprising:
a display section including a plurality of pixel circuits, at least one of the plurality of pixel circuits including:
a light emitting element connected between a first node and a common line;
a switch transistor connected between the first node and a second node;
a driving transistor connected between the second node and a third node;
a storage capacitor connected to a control terminal of the driving transistor via a control node; and
a writing transistor connected between a signal line and the storage capacitor and configured to control a sampling operation,
wherein an emission period during which the light emitting element is made to emit light and a non-emission period during which light emission of the light emitting element is stopped are alternately repeated;
in the emission period, at least one of the plurality of pixel circuits is driven such that:
a driving potential is applied to the third node so that driving current corresponding to voltage across the storage capacitor is supplied to the light emitting element via the driving transistor and the switch transistor;
in the non-emission period, at least one of the plurality of pixel circuits is driven such that:
a potential lower than the driving potential is applied to the third node and the driving transistor, and a terminal voltage of the storage capacitor is set to a potential corresponding to the signal line via the writing transistor, whereby the voltage across the storage capacitor is set to a voltage which is larger than a threshold voltage of the driving transistor, and subsequently the voltage across the storage capacitor is set to a voltage corresponding to the threshold voltage of the driving transistor;
wherein the switch transistor is set in an off state during the non-emission period, and
wherein an anode voltage of the light emitting element is maintained at a voltage obtained by adding the threshold voltage of the driving transistor to a cathode voltage of the light emitting element during the non-emission period.
2. The image display device according to claim 1 , wherein
the terminal voltage of the storage capacitor is, at latest by a starting time of the emission period, set to a voltage related to light emission intensity.
3. The image display device according to claim 1 , wherein
the driving potential and the potential lower than the driving potential are time-divisionally supplied from a power supply line commonly connected to the plurality of pixel circuits.
4. The image display device according to claim 1 , wherein during the non-emission period, an accumulated charge of the storage capacitor flows out to a scanning line via the driving transistor, and a voltage at the second node is lowered.
5. The image display device according to claim 4 , wherein during the non-emission period, a voltage at the control terminal is lowered.
6. The image display device according to claim 1 , wherein the storage capacitor is configured to set a gate-source voltage of the driving transistor.
7. The image display device according to claim 6 , wherein during the non-emission period, at least one of the plurality of pixel circuits is driven such that the control terminal of the driving transistor is set to a potential corresponding to the potential lower than the driving potential, before the voltage across the storage capacitor is set to a voltage depending on the threshold voltage of the driving transistor.
8. An image display device comprising:
a display section including a plurality of pixel circuits, at least one of the plurality of pixel circuits including:
a light emitting element connected between a first node and a common line;
a switch transistor connected between the first node and a second node;
a driving transistor connected between the second node and a third node;
a storage capacitor connected to a control terminal of the driving transistor via a control node; and
a writing transistor connected between a signal line and the storage capacitor and configured to control a sampling operation,
wherein an emission period and a non-emission period of the light emitting element are alternately repeated,
during the non-emission period, at least one of the plurality of pixel circuits is driven such that:
a potential lower than the driving potential is applied to the third node and the driving transistor, and a terminal voltage of the storage capacitor is set to a potential corresponding to the signal line via the writing transistor, whereby the voltage across the storage capacitor is set to a voltage which is larger than a threshold voltage of the driving transistor, and subsequently the voltage across the storage capacitor is set to a voltage depending on the threshold voltage of the driving transistor;
wherein the switch transistor is set in an off state during the non-emission period, and
wherein an anode voltage of the light emitting element is maintained at a voltage obtained by adding the threshold voltage of the driving transistor to a cathode voltage of the light emitting element during the non-emission period.