Driving method of display apparatus
View Patent ↗A method for driving a display apparatus including a current light emitting device which allows a threshold voltage of a driving transistor to be detected independently of an image signal voltage Vsg (j), such that a writing period of the display apparatus can be shortened. The writing period T 3 of the display apparatus is larger than a sum of a time needed for determining image signal voltage Vsg (j) and a time needed for charging a first capacitor which is coupled to a gate of the driving transistor.
1. A driving method of a display apparatus including a plurality of arrayed pixel circuits, each of the pixel circuits including:
a current light emitting device;
a driving transistor supplying current to the current light emitting device;
a first capacitor having a first terminal connected to a gate of the driving transistor;
a second capacitor connected between a second terminal of the first capacitor and a source of the driving transistor;
a first switch applying a reference voltage to the gate of the driving transistor;
a second switch supplying an image signal voltage to a node at which the first and the second capacitors are connected;
a third switch supplying an initialization voltage to the source of the driving transistor, and
a fourth switch configured to short circuit the first capacitor, the driving method comprising:
(a) dividing one-frame period into an initialization period, a threshold detection period, a writing period, and a luminescence period;
(b) applying, in the initialization period, a first differential voltage, defined by a difference between the reference voltage and the initialization voltage, to the second capacitor by setting the second switch OFF, and setting the first, third and fourth switches ON;
(c) reducing, in the threshold detection period, the voltage of the second capacitor by closing a current path formed by the second capacitor and the driving transistor, where the current path is closed by setting second and third switches OFF and first and fourth switches ON;
(d) applying, in the writing period, a second differential voltage, defined by a difference between the reference voltage and the image signal voltage, to the first capacitor by setting the third and fourth switches OFF and first and second switches ON, and
(e) applying, in the luminescence period, a current to the driving transistor and the current light emitting device corresponding to the image signal voltage, by setting first, second, third and fourth switches OFF.
2. The driving method of a display apparatus according to claim 1 , wherein the reference voltage is set to a voltage which is lower than the sum of a low voltage, Vss, and a voltage, Vled, which is the minimum voltage between an anode and a cathode of the current light emitting device when current flows through the current light emitting device.
3. The driving method of a display apparatus according to claim 1 , the initialization voltage is set such that the difference between the initialization voltage and the reference voltage is larger than a threshold voltage of the driving transistor.